fastmcp

# FastMCP - Build MCP Servers in Python

FastMCP is a Python framework for building Model Context Protocol (MCP) servers that expose tools, resources, and prompts to Large Language Models like Claude. This skill provides production-tested patterns, error prevention, and deployment strategies for building robust MCP servers.

## Quick Start

### Installation

```bash
pip install fastmcp
# or
uv pip install fastmcp
```

### Minimal Server

```python
from fastmcp import FastMCP

# MUST be at module level for FastMCP Cloud
mcp = FastMCP("My Server")

@mcp.tool()
async def hello(name: str) -> str:
    """Say hello to someone."""
    return f"Hello, {name}!"

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

**Run it:**
```bash
# Local development
python server.py

# With FastMCP CLI
fastmcp dev server.py

# HTTP mode
python server.py --transport http --port 8000
```

## What's New in v2.14.x (December 2025)

### v2.14.2 (December 31, 2024)
- MCP SDK pinned to <2.x for compatibility
- Supabase provider gains `auth_route` parameter
- Bug fixes: outputSchema `$ref` resolution, OAuth Proxy validation, OpenAPI 3.1 support

### v2.14.1: Sampling with Tools (SEP-1577)
- **`ctx.sample()` now accepts tools** for agentic workflows
- `AnthropicSamplingHandler` promoted from experimental
- `ctx.sample_step()` for single LLM call returning `SampleStep`
- Python 3.13 support added

### v2.14.0: Background Tasks (SEP-1686)
- **Protocol-native background tasks** for long-running operations
- Add `task=True` to async decorators; progress tracking without blocking
- MCP 2025-11-25 specification support
- SEP-1699: SSE polling and event resumability
- SEP-1330: Multi-select enum elicitation schemas
- SEP-1034: Default values for elicitation schemas

**⚠️ Breaking Changes (v2.14.0):**
- `BearerAuthProvider` module removed (use `JWTVerifier` or `OAuthProxy`)
- `Context.get_http_request()` method removed
- `fastmcp.Image` top-level import removed (use `from fastmcp.utilities import Image`)
- `ena