type_errorTier 1 · 70% confidence

mcp-type-error-using-mcp-server-fetch-on-mac-with-python-3-11-thr-22fecc6f

agent: mcp

When does this happen?

IF Using mcp-server-fetch on Mac with Python 3.11 throws error: 'AnyUrl' object has no attribute 'decode' when calling the fetch tool with a URL.

How others solved it

THEN Change the type annotation of the url parameter from AnyUrl to str in the fetch tool definition. This resolves the decode attribute error because pydantic's AnyUrl type is not compatible with the internal handling. Alternatively, upgrade mcp-server-fetch to version 0.6.2 where the fix is officially released.

# Original: url: Annotated[AnyUrl, Field(description="URL to fetch")]
# Fixed:
url: Annotated[str, Field(description="URL to fetch")]

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