Designer tools broken since v1.2 deployment (April 1) — 'Unable to connect' despite Bridge App connected

[dorukardahan]

Description

Designer API tools (element_tool, set_text, query_elements) return "Unable to connect to Webflow Designer" since approximately April 1, 2026. The same setup worked perfectly on March 30.

Bridge App inside Designer shows "Connected to MCP Server" with green status. Read operations via Data API tools work fine. Only Designer write/query operations fail.

Environment

• MCP Config: Remote server ({"type": "http", "url": "https://mcp.webflow.com/mcp"})
• Client: Claude Code CLI (macOS)
• Browser: Chrome 146.0.7680.178 (macOS, Apple Silicon)
• Bridge App: Visible in Designer Apps panel, shows "Connected to MCP Server"
• Site: Production Webflow site, active workspace

Timeline

Date	Status
March 30, 2026	element_tool set_text working perfectly. Changed multiple text elements, published successfully.
April 1, 2026	Same setup, same site, same config. All Designer tools return "Unable to connect to Webflow Designer."
April 2-6, 2026	Retried multiple times. Reconnected OAuth, restarted Chrome, reopened Bridge App. Same error every time.

Reproduction Steps

1. Open Webflow Designer for any site
2. Press E to open Apps panel, launch MCP Bridge App
3. Verify Bridge App shows "Connected to MCP Server"
4. From Claude Code CLI, call element_tool with query_elements (even a simple text search)
5. Returns: {"status":false,"error":"Unable to connect to Webflow Designer..."}

What I've Tried

• Restarting Chrome entirely
• Reopening Bridge App multiple times
• Reconnecting OAuth (cleared ~/.mcp-auth, re-authenticated)
• Chrome launched with --disable-background-timer-throttling --disable-backgrounding-occluded-windows --disable-renderer-backgrounding
• Pinned Designer tab (per FAQ recommendation)
• Kept Designer tab in foreground and clicked to prevent idle
• Opened Designer in separate Chrome window
• Disabled Chrome Memory Saver and Energy Saver
• Tried on a fresh Chrome profile
• Verified Data API tools (e.g., data_pages_tool) work fine — only Designer tools fail

None of these helped.

Suspected Cause

PR #101 (MCP v1.2 Release, merged April 1) introduced:

• New getAccessToken parameter in registerTools (PR refactor: enhance tools registration with access token support #88)
• Stricter Zod validation
• Schema changes (parent_style_name → parent_style_names)

The timing perfectly matches when the tools stopped working. The Bridge App WebSocket connection appears healthy (shows "Connected"), but the server-side auth handshake for Designer tool routing seems broken after v1.2.

This looks similar to #99 (Bridge shows connected but tools fail), which @viratatwebflow fixed quickly on March 26. The v1.2 release may have reintroduced the same regression.

Expected Behavior

element_tool with query_elements should return matching elements when Bridge App shows "Connected to MCP Server."

Actual Behavior

Every Designer tool call returns:

{"status":false,"error":"Unable to connect to Webflow Designer, Please make sure Webflow Designer MCP app is running on Webflow Designer."}

Related Issues

• Webflow MCP Bridge stuck on "Authorizing…" then "can't connect to MCP server" (Claude Desktop, no manual MCP config) #99 — Same symptom pattern (Bridge connected, tools fail). Fixed March 26, possibly regressed in v1.2.
• OAuth token exchange returns HTTP 404 ("Not found" plain text) after successful authorization callback (Cursor 3.x / streamable HTTP) #107 — OAuth token exchange returning 404 after v1.2.
• update_style times out 100% of the time via MCP (both claude.ai connector and Claude Desktop) #79 — Designer write operations hanging (open since Feb 16).

[3backup]

Same issue. MCP is not usable at all right now.