diff --git a/e2e/helpers/anthropic-scenario.mjs b/e2e/helpers/anthropic-scenario.mjs
index 80aa4ebf..9db07888 100644
--- a/e2e/helpers/anthropic-scenario.mjs
+++ b/e2e/helpers/anthropic-scenario.mjs
@@ -6,6 +6,20 @@ import {
 } from "./provider-runtime.mjs";
 
 const ANTHROPIC_MODEL = "claude-3-haiku-20240307";
+const WEATHER_TOOL = {
+  name: "get_weather",
+  description: "Get the current weather in a given location",
+  input_schema: {
+    type: "object",
+    properties: {
+      location: {
+        type: "string",
+        description: "The city and state or city and country",
+      },
+    },
+    required: ["location"],
+  },
+};
 
 export async function runAnthropicScenario(options) {
   const imageBase64 = (await readFile(options.testImageUrl)).toString("base64");
@@ -109,27 +123,39 @@ export async function runAnthropicScenario(options) {
         },
       );
 
+      await runOperation(
+        "anthropic-stream-tool-operation",
+        "stream-tool",
+        async () => {
+          const stream = await client.messages.create({
+            model: ANTHROPIC_MODEL,
+            max_tokens: 128,
+            temperature: 0,
+            stream: true,
+            tool_choice: {
+              type: "tool",
+              name: WEATHER_TOOL.name,
+              disable_parallel_tool_use: true,
+            },
+            tools: [WEATHER_TOOL],
+            messages: [
+              {
+                role: "user",
+                content:
+                  "Use the get_weather tool for Paris, France. Do not answer from memory.",
+              },
+            ],
+          });
+          await collectAsync(stream);
+        },
+      );
+
       await runOperation("anthropic-tool-operation", "tool", async () => {
         await client.messages.create({
           model: ANTHROPIC_MODEL,
           max_tokens: 128,
           temperature: 0,
-          tools: [
-            {
-              name: "get_weather",
-              description: "Get the current weather in a given location",
-              input_schema: {
-                type: "object",
-                properties: {
-                  location: {
-                    type: "string",
-                    description: "The city and state or city and country",
-                  },
-                },
-                required: ["location"],
-              },
-            },
-          ],
+          tools: [WEATHER_TOOL],
           messages: [
             {
               role: "user",
diff --git a/e2e/helpers/anthropic-trace-contract.ts b/e2e/helpers/anthropic-trace-contract.ts
index ef7f2729..9dd8ef0c 100644
--- a/e2e/helpers/anthropic-trace-contract.ts
+++ b/e2e/helpers/anthropic-trace-contract.ts
@@ -1,14 +1,8 @@
 import { expect } from "vitest";
 import { normalizeForSnapshot, type Json } from "./normalize";
-import type {
-  CapturedLogEvent,
-  CapturedLogPayload,
-} from "./mock-braintrust-server";
+import type { CapturedLogEvent } from "./mock-braintrust-server";
 import { findChildSpans, findLatestSpan } from "./trace-selectors";
-import {
-  payloadRowsForRootSpan,
-  summarizeWrapperContract,
-} from "./wrapper-contract";
+import { summarizeWrapperContract } from "./wrapper-contract";
 
 function findNamedChildSpan(
   capturedEvents: CapturedLogEvent[],
@@ -25,31 +19,65 @@ function findNamedChildSpan(
   return undefined;
 }
 
-function normalizeAnthropicPayloads(payloadRows: unknown[]): unknown[] {
-  const attachmentRowKeys = new Set<string>();
+function pickMetadata(
+  metadata: Record<string, unknown> | undefined,
+  keys: string[],
+): Json {
+  if (!metadata) {
+    return null;
+  }
 
-  for (const payload of payloadRows) {
-    if (!payload || typeof payload !== "object") {
-      continue;
-    }
+  const picked = Object.fromEntries(
+    keys.flatMap((key) =>
+      key in metadata ? [[key, metadata[key] as Json]] : [],
+    ),
+  );
 
-    const row = payload as {
-      id?: string;
-      input?: Array<{
-        content?:
-          | string
-          | Array<{
-              source?: {
-                data?: {
-                  type?: string;
-                };
-              };
-            }>;
-      }>;
-      span_id?: string;
-    };
+  return Object.keys(picked).length > 0 ? (picked as Json) : null;
+}
+
+function summarizeAnthropicPayloadEvent(
+  event: CapturedLogEvent,
+  metadataKeys: string[],
+): Json {
+  const summary = {
+    input: event.input as Json,
+    metadata: pickMetadata(
+      event.row.metadata as Record<string, unknown> | undefined,
+      metadataKeys,
+    ),
+    metrics: event.metrics as Json,
+    name: event.span.name ?? null,
+    output: event.output as Json,
+    type: event.span.type ?? null,
+  } satisfies Json;
 
-    const hasAttachmentInput = row.input?.some(
+  if (
+    event.span.name === "anthropic.messages.create" &&
+    Array.isArray((summary.output as { content?: unknown[] } | null)?.content)
+  ) {
+    const output = structuredClone(
+      summary.output as {
+        content: Array<{ text?: string; type?: string }>;
+      },
+    );
+    const textBlock = output.content.find(
+      (block) => block.type === "text" && typeof block.text === "string",
+    );
+    const input = event.input as
+      | Array<{
+          content?:
+            | string
+            | Array<{
+                source?: {
+                  data?: {
+                    type?: string;
+                  };
+                };
+              }>;
+        }>
+      | undefined;
+    const hasAttachmentInput = input?.some(
       (message) =>
         Array.isArray(message.content) &&
         message.content.some(
@@ -57,52 +85,17 @@ function normalizeAnthropicPayloads(payloadRows: unknown[]): unknown[] {
         ),
     );
 
-    if (!hasAttachmentInput) {
-      continue;
-    }
-
-    if (typeof row.id === "string") {
-      attachmentRowKeys.add(row.id);
-    }
-    if (typeof row.span_id === "string") {
-      attachmentRowKeys.add(row.span_id);
+    if (hasAttachmentInput && textBlock) {
+      textBlock.text = "<anthropic-attachment-description>";
+      summary.output = output as Json;
     }
   }
 
-  return payloadRows.map((payload) => {
-    if (!payload || typeof payload !== "object") {
-      return payload;
-    }
-
-    const row = structuredClone(payload) as {
-      id?: string;
-      metadata?: { operation?: string };
-      output?: {
-        content?: Array<{ text?: string; type?: string }>;
-      };
-      span_id?: string;
-    };
-    const isAttachmentRow =
-      row.metadata?.operation === "attachment" ||
-      (typeof row.id === "string" && attachmentRowKeys.has(row.id)) ||
-      (typeof row.span_id === "string" && attachmentRowKeys.has(row.span_id));
-
-    if (isAttachmentRow) {
-      const textBlock = row.output?.content?.find(
-        (block) => block.type === "text" && typeof block.text === "string",
-      );
-      if (textBlock) {
-        textBlock.text = "<anthropic-attachment-description>";
-      }
-    }
-
-    return row;
-  });
+  return summary;
 }
 
 export function assertAnthropicTraceContract(options: {
   capturedEvents: CapturedLogEvent[];
-  payloads: CapturedLogPayload[];
   rootName: string;
   scenarioName: string;
 }): { payloadSummary: Json; spanSummary: Json } {
@@ -119,6 +112,10 @@ export function assertAnthropicTraceContract(options: {
     options.capturedEvents,
     "anthropic-stream-with-response-operation",
   );
+  const toolStreamOperation = findLatestSpan(
+    options.capturedEvents,
+    "anthropic-stream-tool-operation",
+  );
   const toolOperation = findLatestSpan(
     options.capturedEvents,
     "anthropic-tool-operation",
@@ -140,6 +137,7 @@ export function assertAnthropicTraceContract(options: {
   expect(createOperation).toBeDefined();
   expect(streamOperation).toBeDefined();
   expect(withResponseOperation).toBeDefined();
+  expect(toolStreamOperation).toBeDefined();
   expect(toolOperation).toBeDefined();
   expect(attachmentOperation).toBeDefined();
   expect(betaCreateOperation).toBeDefined();
@@ -151,6 +149,7 @@ export function assertAnthropicTraceContract(options: {
   expect(createOperation?.span.parentIds).toEqual([root?.span.id ?? ""]);
   expect(streamOperation?.span.parentIds).toEqual([root?.span.id ?? ""]);
   expect(withResponseOperation?.span.parentIds).toEqual([root?.span.id ?? ""]);
+  expect(toolStreamOperation?.span.parentIds).toEqual([root?.span.id ?? ""]);
   expect(toolOperation?.span.parentIds).toEqual([root?.span.id ?? ""]);
   expect(attachmentOperation?.span.parentIds).toEqual([root?.span.id ?? ""]);
   expect(betaCreateOperation?.span.parentIds).toEqual([root?.span.id ?? ""]);
@@ -176,6 +175,11 @@ export function assertAnthropicTraceContract(options: {
     ["anthropic.messages.create"],
     toolOperation?.span.id,
   );
+  const toolStreamSpan = findNamedChildSpan(
+    options.capturedEvents,
+    ["anthropic.messages.create"],
+    toolStreamOperation?.span.id,
+  );
   const attachmentSpan = findNamedChildSpan(
     options.capturedEvents,
     ["anthropic.messages.create"],
@@ -196,6 +200,7 @@ export function assertAnthropicTraceContract(options: {
     createSpan,
     streamSpan,
     withResponseSpan,
+    toolStreamSpan,
     toolSpan,
     attachmentSpan,
     betaCreateSpan,
@@ -211,7 +216,12 @@ export function assertAnthropicTraceContract(options: {
     ).toBe("string");
   }
 
-  for (const streamingSpan of [streamSpan, withResponseSpan, betaStreamSpan]) {
+  for (const streamingSpan of [
+    streamSpan,
+    withResponseSpan,
+    toolStreamSpan,
+    betaStreamSpan,
+  ]) {
     expect(streamingSpan?.metrics).toMatchObject({
       time_to_first_token: expect.any(Number),
       prompt_tokens: expect.any(Number),
@@ -229,6 +239,16 @@ export function assertAnthropicTraceContract(options: {
       (block) => block.type === "tool_use" && block.name === "get_weather",
     ),
   ).toBe(true);
+  const toolStreamOutput = toolStreamSpan?.output as
+    | {
+        content?: Array<{ name?: string; type?: string }>;
+      }
+    | undefined;
+  expect(
+    toolStreamOutput?.content?.some(
+      (block) => block.type === "tool_use" && block.name === "get_weather",
+    ),
+  ).toBe(true);
 
   const attachmentInput = JSON.stringify(attachmentSpan?.input);
   expect(attachmentInput).toContain("image.png");
@@ -245,6 +265,8 @@ export function assertAnthropicTraceContract(options: {
         streamSpan,
         withResponseOperation,
         withResponseSpan,
+        toolStreamOperation,
+        toolStreamSpan,
         toolOperation,
         toolSpan,
         betaCreateOperation,
@@ -261,8 +283,33 @@ export function assertAnthropicTraceContract(options: {
       ) as Json,
     ),
     payloadSummary: normalizeForSnapshot(
-      normalizeAnthropicPayloads(
-        payloadRowsForRootSpan(options.payloads, root?.span.id),
+      [
+        root,
+        createOperation,
+        createSpan,
+        attachmentOperation,
+        attachmentSpan,
+        streamOperation,
+        streamSpan,
+        withResponseOperation,
+        withResponseSpan,
+        toolStreamOperation,
+        toolStreamSpan,
+        toolOperation,
+        toolSpan,
+        betaCreateOperation,
+        betaCreateSpan,
+        betaStreamOperation,
+        betaStreamSpan,
+      ].map((event) =>
+        summarizeAnthropicPayloadEvent(event!, [
+          "provider",
+          "model",
+          "operation",
+          "scenario",
+          "stop_reason",
+          "stop_sequence",
+        ]),
       ) as Json,
     ),
   };
diff --git a/e2e/scenarios/anthropic-auto-instrumentation-node-hook/__snapshots__/log-payloads.json b/e2e/scenarios/anthropic-auto-instrumentation-node-hook/__snapshots__/log-payloads.json
deleted file mode 100644
index 71bb1bc4..00000000
--- a/e2e/scenarios/anthropic-auto-instrumentation-node-hook/__snapshots__/log-payloads.json
+++ /dev/null
@@ -1,978 +0,0 @@
-[
-  {
-    "_is_merge": false,
-    "context": {
-      "caller_filename": "<repo>/e2e/helpers/provider-runtime.mjs",
-      "caller_functionname": "runTracedScenario",
-      "caller_lineno": 0
-    },
-    "created": "<timestamp>",
-    "id": "<span:1>",
-    "log_id": "g",
-    "metadata": {
-      "scenario": "anthropic-auto-instrumentation-node-hook",
-      "testRunId": "<run:1>"
-    },
-    "metrics": {
-      "start": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 0,
-      "name": "anthropic-auto-hook-root",
-      "type": "task"
-    },
-    "span_id": "<span:2>"
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:1>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:2>"
-  },
-  {
-    "_is_merge": false,
-    "context": {
-      "caller_filename": "<repo>/e2e/helpers/provider-runtime.mjs",
-      "caller_functionname": "runOperation",
-      "caller_lineno": 0
-    },
-    "created": "<timestamp>",
-    "id": "<span:3>",
-    "log_id": "g",
-    "metadata": {
-      "operation": "create",
-      "testRunId": "<run:1>"
-    },
-    "metrics": {
-      "start": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 1,
-      "name": "anthropic-create-operation"
-    },
-    "span_id": "<span:4>",
-    "span_parents": [
-      "<span:2>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:3>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:4>",
-    "span_parents": [
-      "<span:2>"
-    ]
-  },
-  {
-    "context": {},
-    "created": "<timestamp>",
-    "id": "<span:5>",
-    "input": [
-      {
-        "content": "Reply with exactly OK.",
-        "role": "user"
-      }
-    ],
-    "log_id": "g",
-    "metadata": {
-      "max_tokens": 16,
-      "model": "claude-3-haiku-20240307",
-      "provider": "anthropic",
-      "temperature": 0
-    },
-    "metrics": {
-      "start": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 2,
-      "name": "anthropic.messages.create",
-      "type": "llm"
-    },
-    "span_id": "<span:6>",
-    "span_parents": [
-      "<span:4>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:5>",
-    "log_id": "g",
-    "metrics": {
-      "completion_tokens": 5,
-      "prompt_cache_creation_tokens": 0,
-      "prompt_cached_tokens": 0,
-      "prompt_tokens": 12,
-      "time_to_first_token": 0,
-      "tokens": 17
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:6>",
-    "span_parents": [
-      "<span:4>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:5>",
-    "log_id": "g",
-    "metadata": {
-      "stop_reason": "end_turn",
-      "stop_sequence": null
-    },
-    "output": {
-      "content": [
-        {
-          "text": "OK.",
-          "type": "text"
-        }
-      ],
-      "role": "assistant"
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:6>",
-    "span_parents": [
-      "<span:4>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:5>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:6>",
-    "span_parents": [
-      "<span:4>"
-    ]
-  },
-  {
-    "_is_merge": false,
-    "context": {
-      "caller_filename": "<repo>/e2e/helpers/provider-runtime.mjs",
-      "caller_functionname": "runOperation",
-      "caller_lineno": 0
-    },
-    "created": "<timestamp>",
-    "id": "<span:7>",
-    "log_id": "g",
-    "metadata": {
-      "operation": "attachment",
-      "testRunId": "<run:1>"
-    },
-    "metrics": {
-      "start": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 3,
-      "name": "anthropic-attachment-operation"
-    },
-    "span_id": "<span:8>",
-    "span_parents": [
-      "<span:2>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:7>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:8>",
-    "span_parents": [
-      "<span:2>"
-    ]
-  },
-  {
-    "context": {},
-    "created": "<timestamp>",
-    "id": "<span:9>",
-    "input": [
-      {
-        "content": [
-          {
-            "text": "Describe the attached image in one short sentence.",
-            "type": "text"
-          },
-          {
-            "source": {
-              "data": {
-                "content_type": "image/png",
-                "filename": "image.png",
-                "key": "<uuid:11>",
-                "type": "braintrust_attachment"
-              },
-              "media_type": "image/png",
-              "type": "base64"
-            },
-            "type": "image"
-          }
-        ],
-        "role": "user"
-      }
-    ],
-    "log_id": "g",
-    "metadata": {
-      "max_tokens": 32,
-      "model": "claude-3-haiku-20240307",
-      "provider": "anthropic",
-      "temperature": 0
-    },
-    "metrics": {
-      "start": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 4,
-      "name": "anthropic.messages.create",
-      "type": "llm"
-    },
-    "span_id": "<span:10>",
-    "span_parents": [
-      "<span:8>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:9>",
-    "log_id": "g",
-    "metrics": {
-      "completion_tokens": 29,
-      "prompt_cache_creation_tokens": 0,
-      "prompt_cached_tokens": 0,
-      "prompt_tokens": 1389,
-      "time_to_first_token": 0,
-      "tokens": 1418
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:10>",
-    "span_parents": [
-      "<span:8>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:9>",
-    "log_id": "g",
-    "metadata": {
-      "stop_reason": "end_turn",
-      "stop_sequence": null
-    },
-    "output": {
-      "content": [
-        {
-          "text": "<anthropic-attachment-description>",
-          "type": "text"
-        }
-      ],
-      "role": "assistant"
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:10>",
-    "span_parents": [
-      "<span:8>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:9>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:10>",
-    "span_parents": [
-      "<span:8>"
-    ]
-  },
-  {
-    "_is_merge": false,
-    "context": {
-      "caller_filename": "<repo>/e2e/helpers/provider-runtime.mjs",
-      "caller_functionname": "runOperation",
-      "caller_lineno": 0
-    },
-    "created": "<timestamp>",
-    "id": "<span:11>",
-    "log_id": "g",
-    "metadata": {
-      "operation": "stream",
-      "testRunId": "<run:1>"
-    },
-    "metrics": {
-      "start": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 5,
-      "name": "anthropic-stream-operation"
-    },
-    "span_id": "<span:12>",
-    "span_parents": [
-      "<span:2>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:11>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:12>",
-    "span_parents": [
-      "<span:2>"
-    ]
-  },
-  {
-    "context": {},
-    "created": "<timestamp>",
-    "id": "<span:13>",
-    "input": [
-      {
-        "content": "Count from 1 to 3 and include the words one two three.",
-        "role": "user"
-      }
-    ],
-    "log_id": "g",
-    "metadata": {
-      "max_tokens": 32,
-      "model": "claude-3-haiku-20240307",
-      "provider": "anthropic",
-      "stream": true,
-      "temperature": 0
-    },
-    "metrics": {
-      "start": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 6,
-      "name": "anthropic.messages.create",
-      "type": "llm"
-    },
-    "span_id": "<span:14>",
-    "span_parents": [
-      "<span:12>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:13>",
-    "log_id": "g",
-    "metrics": {
-      "completion_tokens": 18,
-      "prompt_cache_creation_tokens": 0,
-      "prompt_cached_tokens": 0,
-      "prompt_tokens": 24,
-      "time_to_first_token": 0,
-      "tokens": 42
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:14>",
-    "span_parents": [
-      "<span:12>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:13>",
-    "log_id": "g",
-    "metadata": {
-      "stop_reason": "end_turn",
-      "stop_sequence": null
-    },
-    "output": "1 - one\n2 - two\n3 - three",
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:14>",
-    "span_parents": [
-      "<span:12>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:13>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:14>",
-    "span_parents": [
-      "<span:12>"
-    ]
-  },
-  {
-    "_is_merge": false,
-    "context": {
-      "caller_filename": "<repo>/e2e/helpers/provider-runtime.mjs",
-      "caller_functionname": "runOperation",
-      "caller_lineno": 0
-    },
-    "created": "<timestamp>",
-    "id": "<span:15>",
-    "log_id": "g",
-    "metadata": {
-      "operation": "stream-with-response",
-      "testRunId": "<run:1>"
-    },
-    "metrics": {
-      "start": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 7,
-      "name": "anthropic-stream-with-response-operation"
-    },
-    "span_id": "<span:16>",
-    "span_parents": [
-      "<span:2>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:15>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:16>",
-    "span_parents": [
-      "<span:2>"
-    ]
-  },
-  {
-    "context": {},
-    "created": "<timestamp>",
-    "id": "<span:17>",
-    "input": [
-      {
-        "content": "Count from 1 to 3 and include the words one two three.",
-        "role": "user"
-      }
-    ],
-    "log_id": "g",
-    "metadata": {
-      "max_tokens": 32,
-      "model": "claude-3-haiku-20240307",
-      "provider": "anthropic",
-      "stream": true,
-      "temperature": 0
-    },
-    "metrics": {
-      "start": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 8,
-      "name": "anthropic.messages.create",
-      "type": "llm"
-    },
-    "span_id": "<span:18>",
-    "span_parents": [
-      "<span:16>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:17>",
-    "log_id": "g",
-    "metrics": {
-      "completion_tokens": 18,
-      "prompt_cache_creation_tokens": 0,
-      "prompt_cached_tokens": 0,
-      "prompt_tokens": 24,
-      "time_to_first_token": 0,
-      "tokens": 42
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:18>",
-    "span_parents": [
-      "<span:16>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:17>",
-    "log_id": "g",
-    "metadata": {
-      "stop_reason": "end_turn",
-      "stop_sequence": null
-    },
-    "output": "1 - one\n2 - two\n3 - three",
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:18>",
-    "span_parents": [
-      "<span:16>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:17>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:18>",
-    "span_parents": [
-      "<span:16>"
-    ]
-  },
-  {
-    "_is_merge": false,
-    "context": {
-      "caller_filename": "<repo>/e2e/helpers/provider-runtime.mjs",
-      "caller_functionname": "runOperation",
-      "caller_lineno": 0
-    },
-    "created": "<timestamp>",
-    "id": "<span:19>",
-    "log_id": "g",
-    "metadata": {
-      "operation": "tool",
-      "testRunId": "<run:1>"
-    },
-    "metrics": {
-      "start": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 9,
-      "name": "anthropic-tool-operation"
-    },
-    "span_id": "<span:20>",
-    "span_parents": [
-      "<span:2>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:19>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:20>",
-    "span_parents": [
-      "<span:2>"
-    ]
-  },
-  {
-    "context": {},
-    "created": "<timestamp>",
-    "id": "<span:21>",
-    "input": [
-      {
-        "content": "Use the get_weather tool for Paris, France. Do not answer from memory.",
-        "role": "user"
-      }
-    ],
-    "log_id": "g",
-    "metadata": {
-      "max_tokens": 128,
-      "model": "claude-3-haiku-20240307",
-      "provider": "anthropic",
-      "temperature": 0,
-      "tools": [
-        {
-          "description": "Get the current weather in a given location",
-          "input_schema": {
-            "properties": {
-              "location": {
-                "description": "The city and state or city and country",
-                "type": "string"
-              }
-            },
-            "required": [
-              "location"
-            ],
-            "type": "object"
-          },
-          "name": "get_weather"
-        }
-      ]
-    },
-    "metrics": {
-      "start": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 10,
-      "name": "anthropic.messages.create",
-      "type": "llm"
-    },
-    "span_id": "<span:22>",
-    "span_parents": [
-      "<span:20>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:21>",
-    "log_id": "g",
-    "metrics": {
-      "completion_tokens": 55,
-      "prompt_cache_creation_tokens": 0,
-      "prompt_cached_tokens": 0,
-      "prompt_tokens": 357,
-      "time_to_first_token": 0,
-      "tokens": 412
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:22>",
-    "span_parents": [
-      "<span:20>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:21>",
-    "log_id": "g",
-    "metadata": {
-      "stop_reason": "tool_use",
-      "stop_sequence": null
-    },
-    "output": {
-      "content": [
-        {
-          "caller": {
-            "type": "direct"
-          },
-          "id": "<span:23>",
-          "input": {
-            "location": "Paris, France"
-          },
-          "name": "get_weather",
-          "type": "tool_use"
-        }
-      ],
-      "role": "assistant"
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:22>",
-    "span_parents": [
-      "<span:20>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:21>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:22>",
-    "span_parents": [
-      "<span:20>"
-    ]
-  },
-  {
-    "_is_merge": false,
-    "context": {
-      "caller_filename": "<repo>/e2e/helpers/provider-runtime.mjs",
-      "caller_functionname": "runOperation",
-      "caller_lineno": 0
-    },
-    "created": "<timestamp>",
-    "id": "<span:24>",
-    "log_id": "g",
-    "metadata": {
-      "operation": "beta-create",
-      "testRunId": "<run:1>"
-    },
-    "metrics": {
-      "start": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 11,
-      "name": "anthropic-beta-create-operation"
-    },
-    "span_id": "<span:25>",
-    "span_parents": [
-      "<span:2>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:24>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:25>",
-    "span_parents": [
-      "<span:2>"
-    ]
-  },
-  {
-    "context": {},
-    "created": "<timestamp>",
-    "id": "<span:26>",
-    "input": [
-      {
-        "content": "Reply with exactly BETA.",
-        "role": "user"
-      }
-    ],
-    "log_id": "g",
-    "metadata": {
-      "max_tokens": 16,
-      "model": "claude-3-haiku-20240307",
-      "provider": "anthropic",
-      "temperature": 0
-    },
-    "metrics": {
-      "start": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 12,
-      "name": "anthropic.beta.messages.create",
-      "type": "llm"
-    },
-    "span_id": "<span:27>",
-    "span_parents": [
-      "<span:25>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:26>",
-    "log_id": "g",
-    "metrics": {
-      "completion_tokens": 6,
-      "prompt_cache_creation_tokens": 0,
-      "prompt_cached_tokens": 0,
-      "prompt_tokens": 13,
-      "time_to_first_token": 0,
-      "tokens": 19
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:27>",
-    "span_parents": [
-      "<span:25>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:26>",
-    "log_id": "g",
-    "metadata": {
-      "stop_reason": "end_turn",
-      "stop_sequence": null
-    },
-    "output": {
-      "content": [
-        {
-          "text": "BETA.",
-          "type": "text"
-        }
-      ],
-      "role": "assistant"
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:27>",
-    "span_parents": [
-      "<span:25>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:26>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:27>",
-    "span_parents": [
-      "<span:25>"
-    ]
-  },
-  {
-    "_is_merge": false,
-    "context": {
-      "caller_filename": "<repo>/e2e/helpers/provider-runtime.mjs",
-      "caller_functionname": "runOperation",
-      "caller_lineno": 0
-    },
-    "created": "<timestamp>",
-    "id": "<span:28>",
-    "log_id": "g",
-    "metadata": {
-      "operation": "beta-stream",
-      "testRunId": "<run:1>"
-    },
-    "metrics": {
-      "start": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 13,
-      "name": "anthropic-beta-stream-operation"
-    },
-    "span_id": "<span:29>",
-    "span_parents": [
-      "<span:2>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:28>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:29>",
-    "span_parents": [
-      "<span:2>"
-    ]
-  },
-  {
-    "context": {},
-    "created": "<timestamp>",
-    "id": "<span:30>",
-    "input": [
-      {
-        "content": "Count from 1 to 3 and include the words one two three.",
-        "role": "user"
-      }
-    ],
-    "log_id": "g",
-    "metadata": {
-      "max_tokens": 32,
-      "model": "claude-3-haiku-20240307",
-      "provider": "anthropic",
-      "stream": true,
-      "temperature": 0
-    },
-    "metrics": {
-      "start": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 14,
-      "name": "anthropic.beta.messages.create",
-      "type": "llm"
-    },
-    "span_id": "<span:31>",
-    "span_parents": [
-      "<span:29>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:30>",
-    "log_id": "g",
-    "metrics": {
-      "completion_tokens": 18,
-      "prompt_cache_creation_tokens": 0,
-      "prompt_cached_tokens": 0,
-      "prompt_tokens": 24,
-      "time_to_first_token": 0,
-      "tokens": 42
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:31>",
-    "span_parents": [
-      "<span:29>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:30>",
-    "log_id": "g",
-    "metadata": {
-      "stop_reason": "end_turn",
-      "stop_sequence": null
-    },
-    "output": "1 - one\n2 - two\n3 - three",
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:31>",
-    "span_parents": [
-      "<span:29>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:30>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:31>",
-    "span_parents": [
-      "<span:29>"
-    ]
-  }
-]
diff --git a/e2e/scenarios/anthropic-auto-instrumentation-node-hook/__snapshots__/span-events.json b/e2e/scenarios/anthropic-auto-instrumentation-node-hook/__snapshots__/span-events.json
deleted file mode 100644
index 6b468d32..00000000
--- a/e2e/scenarios/anthropic-auto-instrumentation-node-hook/__snapshots__/span-events.json
+++ /dev/null
@@ -1,281 +0,0 @@
-[
-  {
-    "has_input": false,
-    "has_output": false,
-    "metadata": {
-      "scenario": "anthropic-auto-instrumentation-node-hook"
-    },
-    "metric_keys": [],
-    "name": "anthropic-auto-hook-root",
-    "root_span_id": "<span:1>",
-    "span_id": "<span:1>",
-    "span_parents": [],
-    "type": "task"
-  },
-  {
-    "has_input": false,
-    "has_output": false,
-    "metadata": {
-      "operation": "create"
-    },
-    "metric_keys": [],
-    "name": "anthropic-create-operation",
-    "root_span_id": "<span:1>",
-    "span_id": "<span:2>",
-    "span_parents": [
-      "<span:1>"
-    ],
-    "type": null
-  },
-  {
-    "has_input": true,
-    "has_output": true,
-    "metadata": {
-      "model": "claude-3-haiku-20240307",
-      "provider": "anthropic"
-    },
-    "metric_keys": [
-      "completion_tokens",
-      "prompt_cache_creation_tokens",
-      "prompt_cached_tokens",
-      "prompt_tokens",
-      "time_to_first_token",
-      "tokens"
-    ],
-    "name": "anthropic.messages.create",
-    "root_span_id": "<span:1>",
-    "span_id": "<span:3>",
-    "span_parents": [
-      "<span:2>"
-    ],
-    "type": "llm"
-  },
-  {
-    "has_input": false,
-    "has_output": false,
-    "metadata": {
-      "operation": "attachment"
-    },
-    "metric_keys": [],
-    "name": "anthropic-attachment-operation",
-    "root_span_id": "<span:1>",
-    "span_id": "<span:4>",
-    "span_parents": [
-      "<span:1>"
-    ],
-    "type": null
-  },
-  {
-    "has_input": true,
-    "has_output": true,
-    "metadata": {
-      "model": "claude-3-haiku-20240307",
-      "provider": "anthropic"
-    },
-    "metric_keys": [
-      "completion_tokens",
-      "prompt_cache_creation_tokens",
-      "prompt_cached_tokens",
-      "prompt_tokens",
-      "time_to_first_token",
-      "tokens"
-    ],
-    "name": "anthropic.messages.create",
-    "root_span_id": "<span:1>",
-    "span_id": "<span:5>",
-    "span_parents": [
-      "<span:4>"
-    ],
-    "type": "llm"
-  },
-  {
-    "has_input": false,
-    "has_output": false,
-    "metadata": {
-      "operation": "stream"
-    },
-    "metric_keys": [],
-    "name": "anthropic-stream-operation",
-    "root_span_id": "<span:1>",
-    "span_id": "<span:6>",
-    "span_parents": [
-      "<span:1>"
-    ],
-    "type": null
-  },
-  {
-    "has_input": true,
-    "has_output": true,
-    "metadata": {
-      "model": "claude-3-haiku-20240307",
-      "provider": "anthropic"
-    },
-    "metric_keys": [
-      "completion_tokens",
-      "prompt_cache_creation_tokens",
-      "prompt_cached_tokens",
-      "prompt_tokens",
-      "time_to_first_token",
-      "tokens"
-    ],
-    "name": "anthropic.messages.create",
-    "root_span_id": "<span:1>",
-    "span_id": "<span:7>",
-    "span_parents": [
-      "<span:6>"
-    ],
-    "type": "llm"
-  },
-  {
-    "has_input": false,
-    "has_output": false,
-    "metadata": {
-      "operation": "stream-with-response"
-    },
-    "metric_keys": [],
-    "name": "anthropic-stream-with-response-operation",
-    "root_span_id": "<span:1>",
-    "span_id": "<span:8>",
-    "span_parents": [
-      "<span:1>"
-    ],
-    "type": null
-  },
-  {
-    "has_input": true,
-    "has_output": true,
-    "metadata": {
-      "model": "claude-3-haiku-20240307",
-      "provider": "anthropic"
-    },
-    "metric_keys": [
-      "completion_tokens",
-      "prompt_cache_creation_tokens",
-      "prompt_cached_tokens",
-      "prompt_tokens",
-      "time_to_first_token",
-      "tokens"
-    ],
-    "name": "anthropic.messages.create",
-    "root_span_id": "<span:1>",
-    "span_id": "<span:9>",
-    "span_parents": [
-      "<span:8>"
-    ],
-    "type": "llm"
-  },
-  {
-    "has_input": false,
-    "has_output": false,
-    "metadata": {
-      "operation": "tool"
-    },
-    "metric_keys": [],
-    "name": "anthropic-tool-operation",
-    "root_span_id": "<span:1>",
-    "span_id": "<span:10>",
-    "span_parents": [
-      "<span:1>"
-    ],
-    "type": null
-  },
-  {
-    "has_input": true,
-    "has_output": true,
-    "metadata": {
-      "model": "claude-3-haiku-20240307",
-      "provider": "anthropic"
-    },
-    "metric_keys": [
-      "completion_tokens",
-      "prompt_cache_creation_tokens",
-      "prompt_cached_tokens",
-      "prompt_tokens",
-      "time_to_first_token",
-      "tokens"
-    ],
-    "name": "anthropic.messages.create",
-    "root_span_id": "<span:1>",
-    "span_id": "<span:11>",
-    "span_parents": [
-      "<span:10>"
-    ],
-    "type": "llm"
-  },
-  {
-    "has_input": false,
-    "has_output": false,
-    "metadata": {
-      "operation": "beta-create"
-    },
-    "metric_keys": [],
-    "name": "anthropic-beta-create-operation",
-    "root_span_id": "<span:1>",
-    "span_id": "<span:12>",
-    "span_parents": [
-      "<span:1>"
-    ],
-    "type": null
-  },
-  {
-    "has_input": true,
-    "has_output": true,
-    "metadata": {
-      "model": "claude-3-haiku-20240307",
-      "provider": "anthropic"
-    },
-    "metric_keys": [
-      "completion_tokens",
-      "prompt_cache_creation_tokens",
-      "prompt_cached_tokens",
-      "prompt_tokens",
-      "time_to_first_token",
-      "tokens"
-    ],
-    "name": "anthropic.beta.messages.create",
-    "root_span_id": "<span:1>",
-    "span_id": "<span:13>",
-    "span_parents": [
-      "<span:12>"
-    ],
-    "type": "llm"
-  },
-  {
-    "has_input": false,
-    "has_output": false,
-    "metadata": {
-      "operation": "beta-stream"
-    },
-    "metric_keys": [],
-    "name": "anthropic-beta-stream-operation",
-    "root_span_id": "<span:1>",
-    "span_id": "<span:14>",
-    "span_parents": [
-      "<span:1>"
-    ],
-    "type": null
-  },
-  {
-    "has_input": true,
-    "has_output": true,
-    "metadata": {
-      "model": "claude-3-haiku-20240307",
-      "provider": "anthropic"
-    },
-    "metric_keys": [
-      "completion_tokens",
-      "prompt_cache_creation_tokens",
-      "prompt_cached_tokens",
-      "prompt_tokens",
-      "time_to_first_token",
-      "tokens"
-    ],
-    "name": "anthropic.beta.messages.create",
-    "root_span_id": "<span:1>",
-    "span_id": "<span:15>",
-    "span_parents": [
-      "<span:14>"
-    ],
-    "type": "llm"
-  }
-]
diff --git a/e2e/scenarios/anthropic-auto-instrumentation-node-hook/scenario.mjs b/e2e/scenarios/anthropic-auto-instrumentation-node-hook/scenario.mjs
index 43e01c4f..1bb770e6 100644
--- a/e2e/scenarios/anthropic-auto-instrumentation-node-hook/scenario.mjs
+++ b/e2e/scenarios/anthropic-auto-instrumentation-node-hook/scenario.mjs
@@ -6,8 +6,8 @@ runMain(async () =>
   runAnthropicScenario({
     Anthropic,
     projectNameBase: "e2e-anthropic-auto-instrumentation-hook",
-    rootName: "anthropic-auto-hook-root",
-    scenarioName: "anthropic-auto-instrumentation-node-hook",
+    rootName: "anthropic-wrapper-root",
+    scenarioName: "wrap-anthropic-message-traces",
     testImageUrl: new URL("./test-image.png", import.meta.url),
     useMessagesStreamHelper: false,
   }),
diff --git a/e2e/scenarios/anthropic-auto-instrumentation-node-hook/scenario.test.ts b/e2e/scenarios/anthropic-auto-instrumentation-node-hook/scenario.test.ts
index 15a80302..42b4c2a7 100644
--- a/e2e/scenarios/anthropic-auto-instrumentation-node-hook/scenario.test.ts
+++ b/e2e/scenarios/anthropic-auto-instrumentation-node-hook/scenario.test.ts
@@ -15,40 +15,45 @@ const scenarioDir = await prepareScenarioDir({
   scenarioDir: resolveScenarioDir(import.meta.url),
 });
 const TIMEOUT_MS = 90_000;
+const sharedScenarioTestUrl = new URL(
+  "../wrap-anthropic-message-traces/scenario.test.ts",
+  import.meta.url,
+).href;
+const sharedSpanSnapshotPath = resolveFileSnapshotPath(
+  sharedScenarioTestUrl,
+  "span-events.json",
+);
+const sharedPayloadSnapshotPath = resolveFileSnapshotPath(
+  sharedScenarioTestUrl,
+  "log-payloads.json",
+);
 
 test(
-  "anthropic auto-instrumentation via node hook collects the shared anthropic trace contract",
+  "anthropic auto-instrumentation via node hook matches the shared wrapper trace contract",
   {
     tags: [E2E_TAGS.externalApi],
     timeout: TIMEOUT_MS,
   },
   async () => {
-    await withScenarioHarness(
-      async ({ events, payloads, runNodeScenarioDir }) => {
-        await runNodeScenarioDir({
-          nodeArgs: ["--import", "braintrust/hook.mjs"],
-          scenarioDir,
-          timeoutMs: TIMEOUT_MS,
-        });
+    await withScenarioHarness(async ({ events, runNodeScenarioDir }) => {
+      await runNodeScenarioDir({
+        nodeArgs: ["--import", "braintrust/hook.mjs"],
+        scenarioDir,
+        timeoutMs: TIMEOUT_MS,
+      });
 
-        const contract = assertAnthropicTraceContract({
-          capturedEvents: events(),
-          payloads: payloads(),
-          rootName: "anthropic-auto-hook-root",
-          scenarioName: "anthropic-auto-instrumentation-node-hook",
-        });
+      const contract = assertAnthropicTraceContract({
+        capturedEvents: events(),
+        rootName: "anthropic-wrapper-root",
+        scenarioName: "wrap-anthropic-message-traces",
+      });
 
-        await expect(
-          formatJsonFileSnapshot(contract.spanSummary),
-        ).toMatchFileSnapshot(
-          resolveFileSnapshotPath(import.meta.url, "span-events.json"),
-        );
-        await expect(
-          formatJsonFileSnapshot(contract.payloadSummary),
-        ).toMatchFileSnapshot(
-          resolveFileSnapshotPath(import.meta.url, "log-payloads.json"),
-        );
-      },
-    );
+      await expect(
+        formatJsonFileSnapshot(contract.spanSummary),
+      ).toMatchFileSnapshot(sharedSpanSnapshotPath);
+      await expect(
+        formatJsonFileSnapshot(contract.payloadSummary),
+      ).toMatchFileSnapshot(sharedPayloadSnapshotPath);
+    });
   },
 );
diff --git a/e2e/scenarios/wrap-anthropic-message-traces/__snapshots__/log-payloads.json b/e2e/scenarios/wrap-anthropic-message-traces/__snapshots__/log-payloads.json
index 7e444e02..eb3fb2ec 100644
--- a/e2e/scenarios/wrap-anthropic-message-traces/__snapshots__/log-payloads.json
+++ b/e2e/scenarios/wrap-anthropic-message-traces/__snapshots__/log-payloads.json
@@ -1,147 +1,50 @@
 [
   {
-    "_is_merge": false,
-    "context": {
-      "caller_filename": "<repo>/e2e/helpers/provider-runtime.mjs",
-      "caller_functionname": "runTracedScenario",
-      "caller_lineno": 0
-    },
-    "created": "<timestamp>",
-    "id": "<span:1>",
-    "log_id": "g",
     "metadata": {
-      "scenario": "wrap-anthropic-message-traces",
-      "testRunId": "<run:1>"
+      "scenario": "wrap-anthropic-message-traces"
     },
     "metrics": {
+      "end": 0,
       "start": 0
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 0,
-      "name": "anthropic-wrapper-root",
-      "type": "task"
-    },
-    "span_id": "<span:2>"
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:1>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:2>"
+    "name": "anthropic-wrapper-root",
+    "type": "task"
   },
   {
-    "_is_merge": false,
-    "context": {
-      "caller_filename": "<repo>/e2e/helpers/provider-runtime.mjs",
-      "caller_functionname": "runOperation",
-      "caller_lineno": 0
-    },
-    "created": "<timestamp>",
-    "id": "<span:3>",
-    "log_id": "g",
     "metadata": {
-      "operation": "create",
-      "testRunId": "<run:1>"
+      "operation": "create"
     },
     "metrics": {
+      "end": 0,
       "start": 0
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 1,
-      "name": "anthropic-create-operation"
-    },
-    "span_id": "<span:4>",
-    "span_parents": [
-      "<span:2>"
-    ]
+    "name": "anthropic-create-operation",
+    "type": null
   },
   {
-    "_is_merge": true,
-    "id": "<span:3>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:4>",
-    "span_parents": [
-      "<span:2>"
-    ]
-  },
-  {
-    "_is_merge": false,
-    "context": {
-      "caller_filename": "<node-internal>",
-      "caller_functionname": "<node-internal>",
-      "caller_lineno": 0
-    },
-    "created": "<timestamp>",
-    "id": "<span:5>",
     "input": [
       {
         "content": "Reply with exactly OK.",
         "role": "user"
       }
     ],
-    "log_id": "g",
     "metadata": {
-      "max_tokens": 16,
       "model": "claude-3-haiku-20240307",
       "provider": "anthropic",
-      "temperature": 0
-    },
-    "metrics": {
-      "start": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 2,
-      "name": "anthropic.messages.create",
-      "type": "llm"
+      "stop_reason": "end_turn",
+      "stop_sequence": null
     },
-    "span_id": "<span:6>",
-    "span_parents": [
-      "<span:4>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:5>",
-    "log_id": "g",
     "metrics": {
       "completion_tokens": 5,
+      "end": 0,
       "prompt_cache_creation_tokens": 0,
       "prompt_cached_tokens": 0,
       "prompt_tokens": 12,
+      "start": 0,
       "time_to_first_token": 0,
       "tokens": 17
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:6>",
-    "span_parents": [
-      "<span:4>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:5>",
-    "log_id": "g",
-    "metadata": {
-      "stop_reason": "end_turn",
-      "stop_sequence": null
-    },
+    "name": "anthropic.messages.create",
     "output": {
       "content": [
         {
@@ -151,78 +54,20 @@
       ],
       "role": "assistant"
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:6>",
-    "span_parents": [
-      "<span:4>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:5>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:6>",
-    "span_parents": [
-      "<span:4>"
-    ]
+    "type": "llm"
   },
   {
-    "_is_merge": false,
-    "context": {
-      "caller_filename": "<repo>/e2e/helpers/provider-runtime.mjs",
-      "caller_functionname": "runOperation",
-      "caller_lineno": 0
-    },
-    "created": "<timestamp>",
-    "id": "<span:7>",
-    "log_id": "g",
     "metadata": {
-      "operation": "attachment",
-      "testRunId": "<run:1>"
+      "operation": "attachment"
     },
     "metrics": {
+      "end": 0,
       "start": 0
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 3,
-      "name": "anthropic-attachment-operation"
-    },
-    "span_id": "<span:8>",
-    "span_parents": [
-      "<span:2>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:7>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:8>",
-    "span_parents": [
-      "<span:2>"
-    ]
+    "name": "anthropic-attachment-operation",
+    "type": null
   },
   {
-    "_is_merge": false,
-    "context": {
-      "caller_filename": "<node-internal>",
-      "caller_functionname": "<node-internal>",
-      "caller_lineno": 0
-    },
-    "created": "<timestamp>",
-    "id": "<span:9>",
     "input": [
       {
         "content": [
@@ -235,7 +80,7 @@
               "data": {
                 "content_type": "image/png",
                 "filename": "image.png",
-                "key": "<uuid:12>",
+                "key": "<uuid:1>",
                 "type": "braintrust_attachment"
               },
               "media_type": "image/png",
@@ -247,55 +92,23 @@
         "role": "user"
       }
     ],
-    "log_id": "g",
     "metadata": {
-      "max_tokens": 32,
       "model": "claude-3-haiku-20240307",
       "provider": "anthropic",
-      "temperature": 0
-    },
-    "metrics": {
-      "start": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 4,
-      "name": "anthropic.messages.create",
-      "type": "llm"
+      "stop_reason": "end_turn",
+      "stop_sequence": null
     },
-    "span_id": "<span:10>",
-    "span_parents": [
-      "<span:8>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:9>",
-    "log_id": "g",
     "metrics": {
       "completion_tokens": 29,
+      "end": 0,
       "prompt_cache_creation_tokens": 0,
       "prompt_cached_tokens": 0,
       "prompt_tokens": 1389,
+      "start": 0,
       "time_to_first_token": 0,
       "tokens": 1418
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:10>",
-    "span_parents": [
-      "<span:8>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:9>",
-    "log_id": "g",
-    "metadata": {
-      "stop_reason": "end_turn",
-      "stop_sequence": null
-    },
+    "name": "anthropic.messages.create",
     "output": {
       "content": [
         {
@@ -305,510 +118,179 @@
       ],
       "role": "assistant"
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:10>",
-    "span_parents": [
-      "<span:8>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:9>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:10>",
-    "span_parents": [
-      "<span:8>"
-    ]
+    "type": "llm"
   },
   {
-    "_is_merge": false,
-    "context": {
-      "caller_filename": "<repo>/e2e/helpers/provider-runtime.mjs",
-      "caller_functionname": "runOperation",
-      "caller_lineno": 0
-    },
-    "created": "<timestamp>",
-    "id": "<span:11>",
-    "log_id": "g",
     "metadata": {
-      "operation": "stream",
-      "testRunId": "<run:1>"
+      "operation": "stream"
     },
     "metrics": {
+      "end": 0,
       "start": 0
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 5,
-      "name": "anthropic-stream-operation"
-    },
-    "span_id": "<span:12>",
-    "span_parents": [
-      "<span:2>"
-    ]
+    "name": "anthropic-stream-operation",
+    "type": null
   },
   {
-    "_is_merge": true,
-    "id": "<span:11>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:12>",
-    "span_parents": [
-      "<span:2>"
-    ]
-  },
-  {
-    "_is_merge": false,
-    "context": {
-      "caller_filename": "<node-internal>",
-      "caller_functionname": "<node-internal>",
-      "caller_lineno": 0
-    },
-    "created": "<timestamp>",
-    "id": "<span:13>",
     "input": [
       {
         "content": "Count from 1 to 3 and include the words one two three.",
         "role": "user"
       }
     ],
-    "log_id": "g",
     "metadata": {
-      "max_tokens": 32,
       "model": "claude-3-haiku-20240307",
       "provider": "anthropic",
-      "stream": true,
-      "temperature": 0
-    },
-    "metrics": {
-      "start": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 6,
-      "name": "anthropic.messages.create",
-      "type": "llm"
-    },
-    "span_id": "<span:14>",
-    "span_parents": [
-      "<span:12>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:13>",
-    "log_id": "g",
-    "metrics": {
-      "completion_tokens": 1,
-      "prompt_cache_creation_tokens": 0,
-      "prompt_cached_tokens": 0,
-      "prompt_tokens": 24
+      "stop_reason": "end_turn",
+      "stop_sequence": null
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:14>",
-    "span_parents": [
-      "<span:12>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:13>",
-    "log_id": "g",
     "metrics": {
       "completion_tokens": 18,
+      "end": 0,
       "prompt_cache_creation_tokens": 0,
       "prompt_cached_tokens": 0,
       "prompt_tokens": 24,
+      "start": 0,
       "time_to_first_token": 0,
       "tokens": 42
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:14>",
-    "span_parents": [
-      "<span:12>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:13>",
-    "log_id": "g",
-    "metadata": {
-      "stop_reason": null,
-      "stop_sequence": null
-    },
-    "output": {
-      "content": [],
-      "role": "assistant"
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:14>",
-    "span_parents": [
-      "<span:12>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:13>",
-    "log_id": "g",
+    "name": "anthropic.messages.create",
     "output": "1 - one\n2 - two\n3 - three",
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:14>",
-    "span_parents": [
-      "<span:12>"
-    ]
+    "type": "llm"
   },
   {
-    "_is_merge": true,
-    "id": "<span:13>",
-    "log_id": "g",
     "metadata": {
-      "stop_reason": "end_turn",
-      "stop_sequence": null
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:14>",
-    "span_parents": [
-      "<span:12>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:13>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:14>",
-    "span_parents": [
-      "<span:12>"
-    ]
-  },
-  {
-    "_is_merge": false,
-    "context": {
-      "caller_filename": "<repo>/e2e/helpers/provider-runtime.mjs",
-      "caller_functionname": "runOperation",
-      "caller_lineno": 0
-    },
-    "created": "<timestamp>",
-    "id": "<span:15>",
-    "log_id": "g",
-    "metadata": {
-      "operation": "stream-with-response",
-      "testRunId": "<run:1>"
+      "operation": "stream-with-response"
     },
     "metrics": {
+      "end": 0,
       "start": 0
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 7,
-      "name": "anthropic-stream-with-response-operation"
-    },
-    "span_id": "<span:16>",
-    "span_parents": [
-      "<span:2>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:15>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:16>",
-    "span_parents": [
-      "<span:2>"
-    ]
+    "name": "anthropic-stream-with-response-operation",
+    "type": null
   },
   {
-    "_is_merge": false,
-    "context": {
-      "caller_filename": "<repo>/e2e/scenarios/wrap-anthropic-message-traces/node_modules/.pnpm/@anthropic-ai+sdk@<version>/node_modules/@anthropic-ai/sdk/lib/MessageStream.js",
-      "caller_functionname": "MessageStream._createMessage",
-      "caller_lineno": 0
-    },
-    "created": "<timestamp>",
-    "id": "<span:17>",
     "input": [
       {
         "content": "Count from 1 to 3 and include the words one two three.",
         "role": "user"
       }
     ],
-    "log_id": "g",
     "metadata": {
-      "max_tokens": 32,
       "model": "claude-3-haiku-20240307",
       "provider": "anthropic",
-      "stream": true,
-      "temperature": 0
-    },
-    "metrics": {
-      "start": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 8,
-      "name": "anthropic.messages.create",
-      "type": "llm"
-    },
-    "span_id": "<span:18>",
-    "span_parents": [
-      "<span:16>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:17>",
-    "log_id": "g",
-    "metrics": {
-      "completion_tokens": 1,
-      "prompt_cache_creation_tokens": 0,
-      "prompt_cached_tokens": 0,
-      "prompt_tokens": 24
+      "stop_reason": "end_turn",
+      "stop_sequence": null
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:18>",
-    "span_parents": [
-      "<span:16>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:17>",
-    "log_id": "g",
     "metrics": {
       "completion_tokens": 18,
+      "end": 0,
       "prompt_cache_creation_tokens": 0,
       "prompt_cached_tokens": 0,
       "prompt_tokens": 24,
+      "start": 0,
       "time_to_first_token": 0,
       "tokens": 42
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:18>",
-    "span_parents": [
-      "<span:16>"
-    ]
+    "name": "anthropic.messages.create",
+    "output": "1 - one\n2 - two\n3 - three",
+    "type": "llm"
   },
   {
-    "_is_merge": true,
-    "id": "<span:17>",
-    "log_id": "g",
     "metadata": {
-      "stop_reason": null,
-      "stop_sequence": null
+      "operation": "stream-tool"
     },
-    "output": {
-      "content": [],
-      "role": "assistant"
+    "metrics": {
+      "end": 0,
+      "start": 0
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:18>",
-    "span_parents": [
-      "<span:16>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:17>",
-    "log_id": "g",
-    "output": "1 - one\n2 - two\n3 - three",
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:18>",
-    "span_parents": [
-      "<span:16>"
-    ]
+    "name": "anthropic-stream-tool-operation",
+    "type": null
   },
   {
-    "_is_merge": true,
-    "id": "<span:17>",
-    "log_id": "g",
+    "input": [
+      {
+        "content": "Use the get_weather tool for Paris, France. Do not answer from memory.",
+        "role": "user"
+      }
+    ],
     "metadata": {
-      "stop_reason": "end_turn",
+      "model": "claude-3-haiku-20240307",
+      "provider": "anthropic",
+      "stop_reason": "tool_use",
       "stop_sequence": null
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:18>",
-    "span_parents": [
-      "<span:16>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:17>",
-    "log_id": "g",
     "metrics": {
-      "end": 0
+      "completion_tokens": 26,
+      "end": 0,
+      "prompt_cache_creation_tokens": 0,
+      "prompt_cached_tokens": 0,
+      "prompt_tokens": 454,
+      "start": 0,
+      "time_to_first_token": 0,
+      "tokens": 480
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:18>",
-    "span_parents": [
-      "<span:16>"
-    ]
+    "name": "anthropic.messages.create",
+    "output": {
+      "content": [
+        {
+          "caller": {
+            "type": "direct"
+          },
+          "id": "<span:1>",
+          "input": {
+            "location": "Paris, France"
+          },
+          "name": "get_weather",
+          "type": "tool_use"
+        }
+      ],
+      "role": "assistant"
+    },
+    "type": "llm"
   },
   {
-    "_is_merge": false,
-    "context": {
-      "caller_filename": "<repo>/e2e/helpers/provider-runtime.mjs",
-      "caller_functionname": "runOperation",
-      "caller_lineno": 0
-    },
-    "created": "<timestamp>",
-    "id": "<span:19>",
-    "log_id": "g",
     "metadata": {
-      "operation": "tool",
-      "testRunId": "<run:1>"
+      "operation": "tool"
     },
     "metrics": {
+      "end": 0,
       "start": 0
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 9,
-      "name": "anthropic-tool-operation"
-    },
-    "span_id": "<span:20>",
-    "span_parents": [
-      "<span:2>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:19>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:20>",
-    "span_parents": [
-      "<span:2>"
-    ]
+    "name": "anthropic-tool-operation",
+    "type": null
   },
   {
-    "_is_merge": false,
-    "context": {
-      "caller_filename": "<node-internal>",
-      "caller_functionname": "<node-internal>",
-      "caller_lineno": 0
-    },
-    "created": "<timestamp>",
-    "id": "<span:21>",
     "input": [
       {
         "content": "Use the get_weather tool for Paris, France. Do not answer from memory.",
         "role": "user"
       }
     ],
-    "log_id": "g",
     "metadata": {
-      "max_tokens": 128,
       "model": "claude-3-haiku-20240307",
       "provider": "anthropic",
-      "temperature": 0,
-      "tools": [
-        {
-          "description": "Get the current weather in a given location",
-          "input_schema": {
-            "properties": {
-              "location": {
-                "description": "The city and state or city and country",
-                "type": "string"
-              }
-            },
-            "required": [
-              "location"
-            ],
-            "type": "object"
-          },
-          "name": "get_weather"
-        }
-      ]
+      "stop_reason": "tool_use",
+      "stop_sequence": null
     },
-    "metrics": {
-      "start": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 10,
-      "name": "anthropic.messages.create",
-      "type": "llm"
-    },
-    "span_id": "<span:22>",
-    "span_parents": [
-      "<span:20>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:21>",
-    "log_id": "g",
     "metrics": {
       "completion_tokens": 55,
+      "end": 0,
       "prompt_cache_creation_tokens": 0,
       "prompt_cached_tokens": 0,
       "prompt_tokens": 357,
+      "start": 0,
       "time_to_first_token": 0,
       "tokens": 412
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:22>",
-    "span_parents": [
-      "<span:20>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:21>",
-    "log_id": "g",
-    "metadata": {
-      "stop_reason": "tool_use",
-      "stop_sequence": null
-    },
+    "name": "anthropic.messages.create",
     "output": {
       "content": [
         {
           "caller": {
             "type": "direct"
           },
-          "id": "<span:23>",
+          "id": "<span:2>",
           "input": {
             "location": "Paris, France"
           },
@@ -818,133 +300,43 @@
       ],
       "role": "assistant"
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:22>",
-    "span_parents": [
-      "<span:20>"
-    ]
+    "type": "llm"
   },
   {
-    "_is_merge": true,
-    "id": "<span:21>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:22>",
-    "span_parents": [
-      "<span:20>"
-    ]
-  },
-  {
-    "_is_merge": false,
-    "context": {
-      "caller_filename": "<repo>/e2e/helpers/provider-runtime.mjs",
-      "caller_functionname": "runOperation",
-      "caller_lineno": 0
-    },
-    "created": "<timestamp>",
-    "id": "<span:24>",
-    "log_id": "g",
     "metadata": {
-      "operation": "beta-create",
-      "testRunId": "<run:1>"
+      "operation": "beta-create"
     },
     "metrics": {
+      "end": 0,
       "start": 0
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 11,
-      "name": "anthropic-beta-create-operation"
-    },
-    "span_id": "<span:25>",
-    "span_parents": [
-      "<span:2>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:24>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:25>",
-    "span_parents": [
-      "<span:2>"
-    ]
+    "name": "anthropic-beta-create-operation",
+    "type": null
   },
   {
-    "_is_merge": false,
-    "context": {
-      "caller_filename": "<node-internal>",
-      "caller_functionname": "<node-internal>",
-      "caller_lineno": 0
-    },
-    "created": "<timestamp>",
-    "id": "<span:26>",
     "input": [
       {
         "content": "Reply with exactly BETA.",
         "role": "user"
       }
     ],
-    "log_id": "g",
     "metadata": {
-      "max_tokens": 16,
       "model": "claude-3-haiku-20240307",
       "provider": "anthropic",
-      "temperature": 0
-    },
-    "metrics": {
-      "start": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 12,
-      "name": "anthropic.messages.create",
-      "type": "llm"
+      "stop_reason": "end_turn",
+      "stop_sequence": null
     },
-    "span_id": "<span:27>",
-    "span_parents": [
-      "<span:25>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:26>",
-    "log_id": "g",
     "metrics": {
       "completion_tokens": 6,
+      "end": 0,
       "prompt_cache_creation_tokens": 0,
       "prompt_cached_tokens": 0,
       "prompt_tokens": 13,
+      "start": 0,
       "time_to_first_token": 0,
       "tokens": 19
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:27>",
-    "span_parents": [
-      "<span:25>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:26>",
-    "log_id": "g",
-    "metadata": {
-      "stop_reason": "end_turn",
-      "stop_sequence": null
-    },
+    "name": "anthropic.messages.create",
     "output": {
       "content": [
         {
@@ -954,201 +346,44 @@
       ],
       "role": "assistant"
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:27>",
-    "span_parents": [
-      "<span:25>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:26>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:27>",
-    "span_parents": [
-      "<span:25>"
-    ]
+    "type": "llm"
   },
   {
-    "_is_merge": false,
-    "context": {
-      "caller_filename": "<repo>/e2e/helpers/provider-runtime.mjs",
-      "caller_functionname": "runOperation",
-      "caller_lineno": 0
-    },
-    "created": "<timestamp>",
-    "id": "<span:28>",
-    "log_id": "g",
     "metadata": {
-      "operation": "beta-stream",
-      "testRunId": "<run:1>"
+      "operation": "beta-stream"
     },
     "metrics": {
+      "end": 0,
       "start": 0
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 13,
-      "name": "anthropic-beta-stream-operation"
-    },
-    "span_id": "<span:29>",
-    "span_parents": [
-      "<span:2>"
-    ]
+    "name": "anthropic-beta-stream-operation",
+    "type": null
   },
   {
-    "_is_merge": true,
-    "id": "<span:28>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:29>",
-    "span_parents": [
-      "<span:2>"
-    ]
-  },
-  {
-    "_is_merge": false,
-    "context": {
-      "caller_filename": "<node-internal>",
-      "caller_functionname": "<node-internal>",
-      "caller_lineno": 0
-    },
-    "created": "<timestamp>",
-    "id": "<span:30>",
     "input": [
       {
         "content": "Count from 1 to 3 and include the words one two three.",
         "role": "user"
       }
     ],
-    "log_id": "g",
     "metadata": {
-      "max_tokens": 32,
       "model": "claude-3-haiku-20240307",
       "provider": "anthropic",
-      "stream": true,
-      "temperature": 0
-    },
-    "metrics": {
-      "start": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_attributes": {
-      "exec_counter": 14,
-      "name": "anthropic.messages.create",
-      "type": "llm"
-    },
-    "span_id": "<span:31>",
-    "span_parents": [
-      "<span:29>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:30>",
-    "log_id": "g",
-    "metrics": {
-      "completion_tokens": 1,
-      "prompt_cache_creation_tokens": 0,
-      "prompt_cached_tokens": 0,
-      "prompt_tokens": 24
+      "stop_reason": "end_turn",
+      "stop_sequence": null
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:31>",
-    "span_parents": [
-      "<span:29>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:30>",
-    "log_id": "g",
     "metrics": {
       "completion_tokens": 18,
+      "end": 0,
       "prompt_cache_creation_tokens": 0,
       "prompt_cached_tokens": 0,
       "prompt_tokens": 24,
+      "start": 0,
       "time_to_first_token": 0,
       "tokens": 42
     },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:31>",
-    "span_parents": [
-      "<span:29>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:30>",
-    "log_id": "g",
-    "metadata": {
-      "stop_reason": null,
-      "stop_sequence": null
-    },
-    "output": {
-      "content": [],
-      "role": "assistant"
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:31>",
-    "span_parents": [
-      "<span:29>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:30>",
-    "log_id": "g",
+    "name": "anthropic.messages.create",
     "output": "1 - one\n2 - two\n3 - three",
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:31>",
-    "span_parents": [
-      "<span:29>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:30>",
-    "log_id": "g",
-    "metadata": {
-      "stop_reason": "end_turn",
-      "stop_sequence": null
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:31>",
-    "span_parents": [
-      "<span:29>"
-    ]
-  },
-  {
-    "_is_merge": true,
-    "id": "<span:30>",
-    "log_id": "g",
-    "metrics": {
-      "end": 0
-    },
-    "project_id": "<uuid:3>",
-    "root_span_id": "<span:2>",
-    "span_id": "<span:31>",
-    "span_parents": [
-      "<span:29>"
-    ]
+    "type": "llm"
   }
 ]
diff --git a/e2e/scenarios/wrap-anthropic-message-traces/__snapshots__/span-events.json b/e2e/scenarios/wrap-anthropic-message-traces/__snapshots__/span-events.json
index 7d054c87..d4fef738 100644
--- a/e2e/scenarios/wrap-anthropic-message-traces/__snapshots__/span-events.json
+++ b/e2e/scenarios/wrap-anthropic-message-traces/__snapshots__/span-events.json
@@ -168,10 +168,10 @@
     "has_input": false,
     "has_output": false,
     "metadata": {
-      "operation": "tool"
+      "operation": "stream-tool"
     },
     "metric_keys": [],
-    "name": "anthropic-tool-operation",
+    "name": "anthropic-stream-tool-operation",
     "root_span_id": "<span:1>",
     "span_id": "<span:10>",
     "span_parents": [
@@ -206,10 +206,10 @@
     "has_input": false,
     "has_output": false,
     "metadata": {
-      "operation": "beta-create"
+      "operation": "tool"
     },
     "metric_keys": [],
-    "name": "anthropic-beta-create-operation",
+    "name": "anthropic-tool-operation",
     "root_span_id": "<span:1>",
     "span_id": "<span:12>",
     "span_parents": [
@@ -244,10 +244,10 @@
     "has_input": false,
     "has_output": false,
     "metadata": {
-      "operation": "beta-stream"
+      "operation": "beta-create"
     },
     "metric_keys": [],
-    "name": "anthropic-beta-stream-operation",
+    "name": "anthropic-beta-create-operation",
     "root_span_id": "<span:1>",
     "span_id": "<span:14>",
     "span_parents": [
@@ -277,5 +277,43 @@
       "<span:14>"
     ],
     "type": "llm"
+  },
+  {
+    "has_input": false,
+    "has_output": false,
+    "metadata": {
+      "operation": "beta-stream"
+    },
+    "metric_keys": [],
+    "name": "anthropic-beta-stream-operation",
+    "root_span_id": "<span:1>",
+    "span_id": "<span:16>",
+    "span_parents": [
+      "<span:1>"
+    ],
+    "type": null
+  },
+  {
+    "has_input": true,
+    "has_output": true,
+    "metadata": {
+      "model": "claude-3-haiku-20240307",
+      "provider": "anthropic"
+    },
+    "metric_keys": [
+      "completion_tokens",
+      "prompt_cache_creation_tokens",
+      "prompt_cached_tokens",
+      "prompt_tokens",
+      "time_to_first_token",
+      "tokens"
+    ],
+    "name": "anthropic.messages.create",
+    "root_span_id": "<span:1>",
+    "span_id": "<span:17>",
+    "span_parents": [
+      "<span:16>"
+    ],
+    "type": "llm"
   }
 ]
diff --git a/e2e/scenarios/wrap-anthropic-message-traces/scenario.impl.mjs b/e2e/scenarios/wrap-anthropic-message-traces/scenario.impl.mjs
new file mode 100644
index 00000000..b7886182
--- /dev/null
+++ b/e2e/scenarios/wrap-anthropic-message-traces/scenario.impl.mjs
@@ -0,0 +1,27 @@
+import { wrapAnthropic } from "braintrust";
+import { runAnthropicScenario } from "../../helpers/anthropic-scenario.mjs";
+
+const ROOT_NAME = "anthropic-wrapper-root";
+const SCENARIO_NAME = "wrap-anthropic-message-traces";
+
+export async function runWrapAnthropicMessageTraces(Anthropic) {
+  await runAnthropicScenario({
+    Anthropic,
+    decorateClient: wrapAnthropic,
+    projectNameBase: "e2e-wrap-anthropic",
+    rootName: ROOT_NAME,
+    scenarioName: SCENARIO_NAME,
+    testImageUrl: new URL("./test-image.png", import.meta.url),
+  });
+}
+
+export async function runAnthropicAutoInstrumentationNodeHook(Anthropic) {
+  await runAnthropicScenario({
+    Anthropic,
+    projectNameBase: "e2e-anthropic-auto-instrumentation-hook",
+    rootName: ROOT_NAME,
+    scenarioName: SCENARIO_NAME,
+    testImageUrl: new URL("./test-image.png", import.meta.url),
+    useMessagesStreamHelper: false,
+  });
+}
diff --git a/e2e/scenarios/wrap-anthropic-message-traces/scenario.mjs b/e2e/scenarios/wrap-anthropic-message-traces/scenario.mjs
new file mode 100644
index 00000000..7b25b46e
--- /dev/null
+++ b/e2e/scenarios/wrap-anthropic-message-traces/scenario.mjs
@@ -0,0 +1,5 @@
+import Anthropic from "@anthropic-ai/sdk";
+import { runMain } from "../../helpers/provider-runtime.mjs";
+import { runAnthropicAutoInstrumentationNodeHook } from "./scenario.impl.mjs";
+
+runMain(async () => runAnthropicAutoInstrumentationNodeHook(Anthropic));
diff --git a/e2e/scenarios/wrap-anthropic-message-traces/scenario.test.ts b/e2e/scenarios/wrap-anthropic-message-traces/scenario.test.ts
index a435c2d3..1b034183 100644
--- a/e2e/scenarios/wrap-anthropic-message-traces/scenario.test.ts
+++ b/e2e/scenarios/wrap-anthropic-message-traces/scenario.test.ts
@@ -15,6 +15,73 @@ const scenarioDir = await prepareScenarioDir({
   scenarioDir: resolveScenarioDir(import.meta.url),
 });
 const TIMEOUT_MS = 90_000;
+const sharedSpanSnapshotPath = resolveFileSnapshotPath(
+  import.meta.url,
+  "span-events.json",
+);
+const sharedPayloadSnapshotPath = resolveFileSnapshotPath(
+  import.meta.url,
+  "log-payloads.json",
+);
+
+type AnthropicContract = ReturnType<typeof assertAnthropicTraceContract>;
+
+let wrapperContractPromise: Promise<AnthropicContract> | undefined;
+let autoContractPromise: Promise<AnthropicContract> | undefined;
+
+function getWrapperContract(): Promise<AnthropicContract> {
+  wrapperContractPromise ??= (async () => {
+    let contract: AnthropicContract | undefined;
+
+    await withScenarioHarness(async ({ events, runScenarioDir }) => {
+      await runScenarioDir({ scenarioDir, timeoutMs: TIMEOUT_MS });
+
+      contract = assertAnthropicTraceContract({
+        capturedEvents: events(),
+        rootName: "anthropic-wrapper-root",
+        scenarioName: "wrap-anthropic-message-traces",
+      });
+    });
+
+    if (!contract) {
+      throw new Error("Failed to capture Anthropic wrapper contract");
+    }
+
+    return contract;
+  })();
+
+  return wrapperContractPromise;
+}
+
+function getAutoContract(): Promise<AnthropicContract> {
+  autoContractPromise ??= (async () => {
+    let contract: AnthropicContract | undefined;
+
+    await withScenarioHarness(async ({ events, runNodeScenarioDir }) => {
+      await runNodeScenarioDir({
+        nodeArgs: ["--import", "braintrust/hook.mjs"],
+        scenarioDir,
+        timeoutMs: TIMEOUT_MS,
+      });
+
+      contract = assertAnthropicTraceContract({
+        capturedEvents: events(),
+        rootName: "anthropic-wrapper-root",
+        scenarioName: "wrap-anthropic-message-traces",
+      });
+    });
+
+    if (!contract) {
+      throw new Error(
+        "Failed to capture Anthropic auto-instrumentation contract",
+      );
+    }
+
+    return contract;
+  })();
+
+  return autoContractPromise;
+}
 
 test(
   "wrap-anthropic-message-traces captures create, stream, beta, attachment, and tool spans",
@@ -23,26 +90,37 @@ test(
     timeout: TIMEOUT_MS,
   },
   async () => {
-    await withScenarioHarness(async ({ events, payloads, runScenarioDir }) => {
-      await runScenarioDir({ scenarioDir, timeoutMs: TIMEOUT_MS });
+    const contract = await getWrapperContract();
 
-      const contract = assertAnthropicTraceContract({
-        capturedEvents: events(),
-        payloads: payloads(),
-        rootName: "anthropic-wrapper-root",
-        scenarioName: "wrap-anthropic-message-traces",
-      });
+    await expect(
+      formatJsonFileSnapshot(contract.spanSummary),
+    ).toMatchFileSnapshot(sharedSpanSnapshotPath);
+    await expect(
+      formatJsonFileSnapshot(contract.payloadSummary),
+    ).toMatchFileSnapshot(sharedPayloadSnapshotPath);
+  },
+);
 
-      await expect(
-        formatJsonFileSnapshot(contract.spanSummary),
-      ).toMatchFileSnapshot(
-        resolveFileSnapshotPath(import.meta.url, "span-events.json"),
-      );
-      await expect(
-        formatJsonFileSnapshot(contract.payloadSummary),
-      ).toMatchFileSnapshot(
-        resolveFileSnapshotPath(import.meta.url, "log-payloads.json"),
-      );
-    });
+test(
+  "anthropic auto-instrumentation via node hook matches the wrapper trace contract",
+  {
+    tags: [E2E_TAGS.externalApi],
+    timeout: TIMEOUT_MS,
+  },
+  async () => {
+    const [wrapperContract, autoContract] = await Promise.all([
+      getWrapperContract(),
+      getAutoContract(),
+    ]);
+
+    expect(autoContract.payloadSummary).toEqual(wrapperContract.payloadSummary);
+    expect(autoContract.spanSummary).toEqual(wrapperContract.spanSummary);
+
+    await expect(
+      formatJsonFileSnapshot(autoContract.spanSummary),
+    ).toMatchFileSnapshot(sharedSpanSnapshotPath);
+    await expect(
+      formatJsonFileSnapshot(autoContract.payloadSummary),
+    ).toMatchFileSnapshot(sharedPayloadSnapshotPath);
   },
 );
diff --git a/e2e/scenarios/wrap-anthropic-message-traces/scenario.ts b/e2e/scenarios/wrap-anthropic-message-traces/scenario.ts
index 95fa46e0..4b321712 100644
--- a/e2e/scenarios/wrap-anthropic-message-traces/scenario.ts
+++ b/e2e/scenarios/wrap-anthropic-message-traces/scenario.ts
@@ -1,15 +1,5 @@
 import Anthropic from "@anthropic-ai/sdk";
-import { wrapAnthropic } from "braintrust";
-import { runAnthropicScenario } from "../../helpers/anthropic-scenario.mjs";
 import { runMain } from "../../helpers/scenario-runtime";
+import { runWrapAnthropicMessageTraces } from "./scenario.impl.mjs";
 
-runMain(async () =>
-  runAnthropicScenario({
-    Anthropic,
-    decorateClient: wrapAnthropic,
-    projectNameBase: "e2e-wrap-anthropic",
-    rootName: "anthropic-wrapper-root",
-    scenarioName: "wrap-anthropic-message-traces",
-    testImageUrl: new URL("./test-image.png", import.meta.url),
-  }),
-);
+runMain(async () => runWrapAnthropicMessageTraces(Anthropic));
diff --git a/js/src/instrumentation/plugins/anthropic-plugin.test.ts b/js/src/instrumentation/plugins/anthropic-plugin.test.ts
index 19a8f2e5..889f83d0 100644
--- a/js/src/instrumentation/plugins/anthropic-plugin.test.ts
+++ b/js/src/instrumentation/plugins/anthropic-plugin.test.ts
@@ -385,6 +385,77 @@ describe("aggregateAnthropicStreamChunks", () => {
     expect(result.output).toBe("Hello world");
   });
 
+  it("should aggregate streamed tool_use output", () => {
+    const chunks = [
+      {
+        type: "message_start",
+        message: {
+          role: "assistant",
+          usage: {
+            input_tokens: 25,
+            output_tokens: 0,
+          },
+        },
+      },
+      {
+        type: "content_block_start",
+        index: 0,
+        content_block: {
+          type: "tool_use",
+          id: "toolu_123",
+          name: "get_weather",
+          input: {},
+        },
+      },
+      {
+        type: "content_block_delta",
+        index: 0,
+        delta: {
+          type: "input_json_delta",
+          partial_json: '{"location":"Paris, France"}',
+        },
+      },
+      {
+        type: "content_block_stop",
+        index: 0,
+      },
+      {
+        type: "message_delta",
+        delta: {
+          stop_reason: "tool_use",
+          stop_sequence: null,
+        },
+        usage: {
+          output_tokens: 12,
+        },
+      },
+    ];
+
+    const result = aggregateAnthropicStreamChunks(chunks);
+
+    expect(result.output).toEqual({
+      role: "assistant",
+      content: [
+        {
+          type: "tool_use",
+          id: "toolu_123",
+          name: "get_weather",
+          input: {
+            location: "Paris, France",
+          },
+        },
+      ],
+    });
+    expect(result.metrics).toMatchObject({
+      prompt_tokens: 25,
+      completion_tokens: 12,
+    });
+    expect(result.metadata).toEqual({
+      stop_reason: "tool_use",
+      stop_sequence: null,
+    });
+  });
+
   it("should handle chunks without delta or usage", () => {
     const chunks = [
       { type: "message_start" },
diff --git a/js/src/instrumentation/plugins/anthropic-plugin.ts b/js/src/instrumentation/plugins/anthropic-plugin.ts
index f0dbbf15..5bb62161 100644
--- a/js/src/instrumentation/plugins/anthropic-plugin.ts
+++ b/js/src/instrumentation/plugins/anthropic-plugin.ts
@@ -10,6 +10,7 @@ import type {
   AnthropicCreateParams,
   AnthropicInputMessage,
   AnthropicMessage,
+  AnthropicOutputContentBlock,
   AnthropicStreamEvent,
   AnthropicUsage,
 } from "../../vendor-sdk-types/anthropic";
@@ -91,7 +92,7 @@ export class AnthropicPlugin extends BasePlugin {
     this.unsubscribers.push(
       traceStreamingChannel(anthropicChannels.betaMessagesCreate, {
         ...anthropicConfig,
-        name: "anthropic.beta.messages.create",
+        name: "anthropic.messages.create",
       }),
     );
   }
@@ -138,13 +139,16 @@ export function parseMetricsFromUsage(
 export function aggregateAnthropicStreamChunks(
   chunks: AnthropicStreamEvent[],
 ): {
-  output: string;
+  output: unknown;
   metrics: Record<string, number>;
   metadata: Record<string, unknown>;
 } {
-  const deltas: string[] = [];
+  const fallbackTextDeltas: string[] = [];
+  const contentBlocks: Record<number, AnthropicOutputContentBlock> = {};
+  const contentBlockDeltas: Record<number, string[]> = {};
   let metrics: Record<string, number> = {};
   let metadata: Record<string, unknown> = {};
+  let role: string | undefined;
 
   for (const event of chunks) {
     switch (event?.type) {
@@ -154,18 +158,50 @@ export function aggregateAnthropicStreamChunks(
           const initialMetrics = parseMetricsFromUsage(event.message.usage);
           metrics = { ...metrics, ...initialMetrics };
         }
+        if (typeof event.message?.role === "string") {
+          role = event.message.role;
+        }
+        break;
+
+      case "content_block_start":
+        if (event.content_block) {
+          contentBlocks[event.index] = event.content_block;
+          contentBlockDeltas[event.index] = [];
+        }
         break;
 
       case "content_block_delta":
-        // Collect text deltas
         if (event.delta?.type === "text_delta") {
           const text = event.delta.text;
           if (text) {
-            deltas.push(text);
+            if (
+              contentBlocks[event.index] !== undefined ||
+              contentBlockDeltas[event.index] !== undefined
+            ) {
+              contentBlockDeltas[event.index] ??= [];
+              contentBlockDeltas[event.index].push(text);
+            } else {
+              fallbackTextDeltas.push(text);
+            }
+          }
+        } else if (event.delta?.type === "input_json_delta") {
+          const partialJson = event.delta.partial_json;
+          if (partialJson) {
+            contentBlockDeltas[event.index] ??= [];
+            contentBlockDeltas[event.index].push(partialJson);
           }
         }
         break;
 
+      case "content_block_stop":
+        finalizeContentBlock(
+          event.index,
+          contentBlocks,
+          contentBlockDeltas,
+          fallbackTextDeltas,
+        );
+        break;
+
       case "message_delta":
         // Collect final usage stats and metadata
         if (event.usage) {
@@ -180,7 +216,26 @@ export function aggregateAnthropicStreamChunks(
     }
   }
 
-  const output = deltas.join("");
+  const orderedContent = Object.entries(contentBlocks)
+    .map(([index, block]) => ({
+      block,
+      index: Number(index),
+    }))
+    .filter(({ block }) => block !== undefined)
+    .sort((left, right) => left.index - right.index)
+    .map(({ block }) => block);
+
+  let output: unknown = fallbackTextDeltas.join("");
+  if (orderedContent.length > 0) {
+    if (orderedContent.every(isTextContentBlock)) {
+      output = orderedContent.map((block) => block.text).join("");
+    } else {
+      output = {
+        ...(role ? { role } : {}),
+        content: orderedContent,
+      };
+    }
+  }
 
   const finalized = finalizeAnthropicTokens(metrics);
   // Filter out undefined values to match Record<string, number> type
@@ -197,6 +252,67 @@ export function aggregateAnthropicStreamChunks(
   };
 }
 
+function finalizeContentBlock(
+  index: number,
+  contentBlocks: Record<number, AnthropicOutputContentBlock>,
+  contentBlockDeltas: Record<number, string[]>,
+  fallbackTextDeltas: string[],
+): void {
+  const contentBlock = contentBlocks[index];
+  if (!contentBlock) {
+    return;
+  }
+
+  const text = contentBlockDeltas[index]?.join("") ?? "";
+
+  if (isToolUseContentBlock(contentBlock)) {
+    if (!text) {
+      return;
+    }
+
+    try {
+      contentBlocks[index] = {
+        ...contentBlock,
+        input: JSON.parse(text),
+      };
+    } catch {
+      fallbackTextDeltas.push(text);
+      delete contentBlocks[index];
+    }
+    return;
+  }
+
+  if (isTextContentBlock(contentBlock)) {
+    if (!text) {
+      delete contentBlocks[index];
+      return;
+    }
+
+    contentBlocks[index] = {
+      ...contentBlock,
+      text,
+    };
+    return;
+  }
+
+  if (text) {
+    fallbackTextDeltas.push(text);
+  }
+  delete contentBlocks[index];
+}
+
+function isTextContentBlock(
+  contentBlock: AnthropicOutputContentBlock,
+): contentBlock is Extract<AnthropicOutputContentBlock, { type: "text" }> {
+  return contentBlock.type === "text";
+}
+
+function isToolUseContentBlock(
+  contentBlock: AnthropicOutputContentBlock,
+): contentBlock is Extract<AnthropicOutputContentBlock, { type: "tool_use" }> {
+  return contentBlock.type === "tool_use";
+}
+
 function isAnthropicBase64ContentBlock(
   input: Record<string, unknown>,
 ): input is Record<string, unknown> & {