The Model Context Protocol (MCP) is a new, standardized way to provide context and tools to your LLMs, and FastMCP makes building MCP servers and clients simple and intuitive. Create tools, expose resources, define prompts, and more with clean, Pythonic code:

from fastmcp import FastMCP

mcp = FastMCP("Demo 🚀")

@mcp.tool()
def add(a: int, b: int) -> int:
    """Add two numbers"""
    return a + b

if __name__ == "__main__":
    mcp.run()

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FastMCP and the Official MCP SDK

FastMCP is the standard framework for building MCP servers and clients. FastMCP 1.0 was incorporated into the official MCP Python SDK.

This is FastMCP 2.0, the actively maintained version that significantly expands on 1.0’s basic server-building capabilities by introducing full client support, server composition, OpenAPI/FastAPI integration, remote server proxying, built-in testing tools, and more.

FastMCP 2.0 is the complete toolkit for modern AI applications. Ready to upgrade or get started? Follow the installation instructions, which include specific steps for upgrading from the official MCP SDK.

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What is MCP?

The Model Context Protocol lets you build servers that expose data and functionality to LLM applications in a secure, standardized way. It is often described as “the USB-C port for AI”, providing a uniform way to connect LLMs to resources they can use. It may be easier to think of it as an API, but specifically designed for LLM interactions. MCP servers can:

  • Expose data through Resources (think of these sort of like GET endpoints; they are used to load information into the LLM’s context)
  • Provide functionality through Tools (sort of like POST endpoints; they are used to execute code or otherwise produce a side effect)
  • Define interaction patterns through Prompts (reusable templates for LLM interactions)
  • And more!

There is a low-level Python SDK available for implementing the protocol directly, but FastMCP aims to make that easier by providing a high-level, Pythonic interface.

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Why FastMCP?

The MCP protocol is powerful but implementing it involves a lot of boilerplate - server setup, protocol handlers, content types, error management. FastMCP handles all the complex protocol details and server management, so you can focus on building great tools. It’s designed to be high-level and Pythonic; in most cases, decorating a function is all you need.

While the core server concepts of FastMCP 1.0 laid the groundwork and were contributed to the official MCP SDK, FastMCP 2.0 (this project) is the actively developed successor, adding significant enhancements and entirely new capabilities like a powerful client library, server proxying, composition patterns, and much more.

FastMCP aims to be:

🚀 Fast: High-level interface means less code and faster development

🍀 Simple: Build MCP servers with minimal boilerplate

🐍 Pythonic: Feels natural to Python developers

🔍 Complete: FastMCP aims to provide a full implementation of the core MCP specification

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llms.txt

This documentation is also available in llms.txt format, which is a simple markdown standard that LLMs can consume easily.

There are two ways to access the LLM-friendly documentation:

  • llms.txt is essentially a sitemap, listing all the pages in the documentation.
  • llms-full.txt contains the entire documentation. Note this may exceed the context window of your LLM.