fix: add explicit type annotation for call_tool decorator#1826
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Kludex merged 3 commits intomodelcontextprotocol:mainfrom Jan 6, 2026
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Replace `Callable[..., Awaitable[...]]` with a concrete `CallToolHandler` type alias that specifies the exact expected function signature `(str, dict[str, Any]) -> Awaitable[...]`. This enables static type checkers (mypy/pyright) to validate decorated functions without requiring `# type: ignore` comments, making the `py.typed` marker actually useful. Fixes modelcontextprotocol#1822 Github-Issue: modelcontextprotocol#1822
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Pull request overview
This pull request improves type clarity in the call_tool decorator by introducing a CallToolHandler type alias. The change makes the function signature more explicit and easier to read by extracting the inline type definition into a reusable type alias.
- Added a
CallToolHandlertype alias that explicitly defines handler function signatures withstranddict[str, Any]parameters - Updated the
call_tooldecorator to use the new type alias, replacing the previous inlineCallable[..., Awaitable[...]]definition
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maxisbey
reviewed
Jan 5, 2026
Kludex
approved these changes
Jan 6, 2026
Kludex
changed the title
call_tool decorator
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This pull request introduces a type alias to clarify and simplify the function signature of handlers registered with
call_toolin theserver.pymodule. The main change is the introduction and use of theCallToolHandlertype alias, which improves code readability and maintainability.Type hinting and handler signature improvements:
CallToolHandlertype alias to explicitly define the expected function signature for call tool handler functions inserver.py.call_tooldecorator to use the newCallToolHandlertype alias, replacing the previous inline type definition for better clarity and consistency.