PrefectHQ/fastmcp

🚀 The fast, Pythonic way to build MCP servers and clients.

What it solves

FastMCP simplifies the process of building applications that use the Model Context Protocol (MCP). MCP is designed to connect LLMs to external tools, data, and resources, but implementing it manually can be complex. FastMCP abstracts away the boilerplate, handling schema generation, validation, protocol negotiation, and lifecycle management so developers can focus on their core logic.

How it works

FastMCP provides a high-level framework that allows you to define MCP servers, clients, and interactive apps using simple Python decorators. By wrapping standard Python functions with @mcp.tool, the framework automatically generates the necessary JSON schemas, documentation, and validation logic required for an LLM to understand and execute those tools. It manages the underlying transport and authentication, ensuring seamless communication between the LLM and your data or services.

Who it’s for

This project is for developers building AI agents or LLM-powered applications who need a reliable, standardized way to connect their models to external tools, databases, or APIs using the Model Context Protocol.

Highlights

  • Automated Schema Generation: Automatically converts Python functions into MCP-compliant tools with full documentation and validation.
  • Full Protocol Support: Manages transport negotiation, authentication, and lifecycle management for both servers and clients.
  • Interactive Apps: Supports rendering interactive UIs directly within the LLM conversation interface.
  • Multi-Language Support: Offers a feature-equivalent TypeScript counterpart for developers working outside of Python.
  • Production-Ready: Designed to integrate with enterprise-grade gateways for scaling, governance, and observability.

Related

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    A collection of reference implementations for the Model Context Protocol, designed to help developers learn how to build secure, standardized tool and data integrations for Large Language Models.

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