Fast MCP Server

Build MCP servers with Python functions using automatic schema and validation generation.

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53★ 26,793PythonApache-2.0

Overview

FastMCP serves as a development framework designed to simplify the creation of Model Context Protocol (MCP) servers. By wrapping Python functions with its decorators, developers can automatically generate JSON schemas, handle input validation, and provide documentation for LLMs without manual configuration. It manages the complexities of protocol lifecycles, transport negotiation, and authentication. The framework is used to expose tools, resources, and prompts directly to AI models. Since its incorporation into the official Python SDK, it has become a widely used tool for building MCP-compliant infrastructure, allowing developers to focus on application logic while the framework handles the underlying protocol requirements.

Our verdict

FastMCP carries a high risk level with a security score of 53/100. Key concerns include that its OAuth, authentication, and read-only mode support have not yet been editorially reviewed, which could pose risks for production environments requiring strict access control. Due to these unverified security components, it is currently best suited for prototyping and internal development rather than high-stakes, public-facing infrastructure.

Zero direct dependencies minimize supply-chain surface area.
Automates schema generation, validation, and documentation from code.
Maintains an active development cycle with daily commits.
Supported by a large community of over 100 contributors.

OAuth and authentication mechanisms lack formal security review.
Read-only mode support is currently unverified.
Security score of 53/100 indicates high risk.

Compatibility

Client	Local	Docker	Remote	Read-only
Claude Desktop
Cursor
VS Code
Windsurf
ChatGPT

Frequently asked questions

›What is the recommended method for installing FastMCP?

We recommend installing FastMCP using uv.

›What should I do if the import fails after upgrading from FastMCP 3.2 or earlier?

If you encounter an import error after a pip upgrade, you should run 'pip install --force-reinstall fastmcp'. Users of uv are unaffected by this issue.

›How do I define a tool using FastMCP?

You can declare a tool by using the @mcp.tool decorator on a standard Python function, which automatically handles schema generation, validation, and documentation.

›Does FastMCP manage low-level protocol details?

Yes, FastMCP manages transport negotiation, authentication, and the protocol lifecycle automatically when connecting to a server.

›Can FastMCP be used to build interactive UIs?

Yes, FastMCP Apps allow you to create interactive UIs that are rendered directly within the conversation.