fix: correct return type annotation for MCPServer.call_tool()#2159
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giulio-leone wants to merge 1 commit intomodelcontextprotocol:mainfrom
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fix: correct return type annotation for MCPServer.call_tool()#2159giulio-leone wants to merge 1 commit intomodelcontextprotocol:mainfrom
giulio-leone wants to merge 1 commit intomodelcontextprotocol:mainfrom
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The return type was annotated as Sequence[ContentBlock] | dict[str, Any] but the actual return types from convert_result() are: - Sequence[ContentBlock] (when no output schema) - tuple[Sequence[ContentBlock], dict[str, Any]] (when output schema is set) - CallToolResult (when tool returns CallToolResult directly) The dict[str, Any] variant was unreachable, as noted by a TODO comment in _handle_call_tool. Update the annotation to match the actual behavior and remove the stale TODO. Fixes modelcontextprotocol#1251 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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This is not the way to go, we need to drop the tuple on the return statement. |
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Summary
Fixes #1251
The return type annotation for
MCPServer.call_tool()wasSequence[ContentBlock] | dict[str, Any], but the actual return types fromconvert_result()are:Sequence[ContentBlock]— when no output schema is definedtuple[Sequence[ContentBlock], dict[str, Any]]— when an output schema is setCallToolResult— when the tool function returns aCallToolResultdirectlyThe
dict[str, Any]variant was unreachable, as noted by an inline TODO comment in_handle_call_tool. This could mislead subclass authors into returning a baredictfromcall_tool()overrides, which would hit the dead-code fallback path instead of being handled correctly.Changes
call_tool()toSequence[ContentBlock] | tuple[Sequence[ContentBlock], dict[str, Any]] | CallToolResultTest Results
475 server tests pass (2 consecutive clean runs).