# FastMCP — Build MCP Servers in Python, Fast

> The fast, Pythonic way to build MCP servers and clients. Clean decorator API, automatic type validation, built-in testing, and OpenAPI integration. 24K+ GitHub stars.

## Install

Merge the JSON below into your `.mcp.json`:

## Quick Use

```bash
pip install fastmcp
```

```python
from fastmcp import FastMCP

mcp = FastMCP("My Server")

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

mcp.run()
```

---

## Intro

FastMCP is the fastest way to build MCP (Model Context Protocol) servers and clients in Python. It provides a clean, decorator-based API that handles all the protocol complexity — type validation, error handling, serialization — so you can focus on building tools. 24,000+ GitHub stars, actively maintained.

**Best for**: Python developers building MCP servers for AI coding tools
**Works with**: Claude Code, Cursor, Gemini CLI, VS Code, any MCP client

---

## Key Features

### Simple Decorator API
Define tools, resources, and prompts with Python decorators — no boilerplate:
```python
@mcp.tool()
def search_files(query: str, max_results: int = 10) -> list[str]:
    """Search files matching query."""
    ...
```

### Automatic Type Validation
Uses Pydantic for automatic request/response validation from type hints.

### Built-in Testing
```python
from fastmcp.testing import MCPTestClient
async with MCPTestClient(mcp) as client:
    result = await client.call_tool("add", {"a": 1, "b": 2})
    assert result == 3
```

### MCP Client
Also includes a Python MCP client for connecting to any MCP server.

### OpenAPI Integration
Import existing OpenAPI/Swagger specs to auto-generate MCP tools from REST APIs.

---

### FAQ

**Q: What is FastMCP?**
A: FastMCP is a Python framework for building MCP servers and clients with a clean decorator API. It handles protocol complexity, type validation, and serialization automatically. 24K+ stars on GitHub.

**Q: How is FastMCP different from the official MCP SDK?**
A: FastMCP provides a higher-level, more Pythonic API with decorators, automatic type validation, built-in testing, and OpenAPI integration — reducing boilerplate significantly.

---

## Source & Thanks

> Created by [PrefectHQ](https://github.com/PrefectHQ). Licensed under Apache 2.0.
> [PrefectHQ/fastmcp](https://github.com/PrefectHQ/fastmcp) — 24,000+ GitHub stars

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Source: https://tokrepo.com/en/workflows/a17a107c-c77e-4c3f-ae09-d2fd985eba93
Author: MCP Hub