FastMCP
Python framework for building MCP (Model Context Protocol) servers in a few lines. One @mcp.tool decorator on your Python function, FastMCP auto-generates schema, validation and docs. De facto standard according to its maintainers (Prefect): some version of FastMCP powers 70% of MCP servers across all languages, around a million downloads a day.
Strengths
- Single @mcp.tool decorator, zero MCP protocol boilerplate to write
- Very widespread (70% of MCP servers per Prefect), compatible with Claude Code, Cursor, Windsurf
- Covers Servers, Clients AND Apps (interactive UIs rendered in the conversation)
Limitations
- Python only: for Node/TypeScript, use FastMCP for TypeScript (official sibling) or the official MCP SDK
- Requires understanding the MCP model (resources, tools, prompts) before starting
Best for
- Python devs who want to expose their functions, APIs or DBs to Claude Code in under an hour
- Teams wanting to connect their business tools to their LLM agents via an internal MCP