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fix: replace deprecated description kwarg with instructions in FastMCP#1

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max8989 wants to merge 1 commit intoryu-tada:mainfrom
max8989:fix/fastmcp-description-kwarg
Open

fix: replace deprecated description kwarg with instructions in FastMCP#1
max8989 wants to merge 1 commit intoryu-tada:mainfrom
max8989:fix/fastmcp-description-kwarg

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@max8989 max8989 commented Feb 23, 2026

Problem

FastMCP.__init__() no longer accepts a description keyword argument in
recent versions of the mcp package, causing the server to crash on startup:
TypeError: FastMCP.init() got an unexpected keyword argument 'description'

Fix

Replaced description= with instructions=, which is the correct parameter
name in the current FastMCP API.

Testing

Verified the server starts successfully after the change:

  • Tested with mcp==1.26.0 on Python 3.14.3

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