# MCP Python SDK

<div align="center">

<strong>Python implementation of the Model Context Protocol (MCP)</strong>

[![PyPI][pypi-badge]][pypi-url]
[![MIT licensed][mit-badge]][mit-url]
[![Python Version][python-badge]][python-url]
[![Documentation][docs-badge]][docs-url]
[![Specification][spec-badge]][spec-url]
[![GitHub Discussions][discussions-badge]][discussions-url]

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## Table of Contents

- [Overview](#overview)
- [Installation](#installation)
- [Writing MCP Servers](#writing-mcp-servers)
  - [FastMCP (Recommended)](#fastmcp-recommended)
  - [Low-Level Server (Advanced)](#low-level-server-advanced)
- [Writing MCP Clients](#writing-mcp-clients)
- [MCP Primitives](#mcp-primitives)
  - [Server Capabilities](#server-capabilities)
- [Documentation](#documentation)
- [Contributing](#contributing)
- [License](#license)

[pypi-badge]: https://img.shields.io/pypi/v/mcp.svg
[pypi-url]: https://pypi.org/project/mcp/
[mit-badge]: https://img.shields.io/pypi/l/mcp.svg
[mit-url]: https://github.com/modelcontextprotocol/python-sdk/blob/main/LICENSE
[python-badge]: https://img.shields.io/pypi/pyversions/mcp.svg
[python-url]: https://www.python.org/downloads/
[docs-badge]: https://img.shields.io/badge/docs-modelcontextprotocol.io-blue.svg
[docs-url]: https://modelcontextprotocol.io
[spec-badge]: https://img.shields.io/badge/spec-spec.modelcontextprotocol.io-blue.svg
[spec-url]: https://spec.modelcontextprotocol.io
[discussions-badge]: https://img.shields.io/github/discussions/modelcontextprotocol/python-sdk
[discussions-url]: https://github.com/modelcontextprotocol/python-sdk/discussions


## Overview

The Model Context Protocol allows applications to provide context for LLMs in a standardized way, separating the concerns of providing context from the actual LLM interaction. This Python SDK implements the full MCP specification, making it easy to:

- Build MCP clients that can connect to any MCP server
- Create MCP servers that expose resources, prompts and tools
- Use standard transports like stdio and SSE
- Handle all MCP protocol messages and lifecycle events

## Installation

We recommend the use of [uv](https://docs.astral.sh/uv/) to manage your Python projects:

```bash
uv add mcp
```

Alternatively, add mcp to your `requirements.txt`:
```
pip install mcp
# or add to requirements.txt
pip install -r requirements.txt
```

## Writing MCP Servers

The MCP Python SDK provides two ways to implement servers:

### FastMCP (Recommended)

FastMCP provides a high-level, Pythonic interface for building MCP servers quickly and easily. It handles all the complex protocol details so you can focus on building great tools:

```python
from mcp.server.fastmcp import FastMCP

mcp = FastMCP("Demo")

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

@mcp.resource("greeting://{name}")
def get_greeting(name: str) -> str:
    """Get a personalized greeting"""
    return f"Hello, {name}!"
```

FastMCP features:
- Simple, decorator-based API
- Automatic type handling and validation
- Built-in support for async functions
- Progress reporting and logging
- Resource templating
- Image handling

### Low-Level Server (Advanced)

For more control, you can use the low-level server implementation directly. This gives you full access to the protocol and allows you to customize every aspect of your server:

```python
from mcp.server.lowlevel import Server, NotificationOptions
from mcp.server.models import InitializationOptions
import mcp.server.stdio
import mcp.types as types

# Create a server instance
server = Server("example-server")

@server.list_prompts()
async def handle_list_prompts() -> list[types.Prompt]:
    return [
        types.Prompt(
            name="example-prompt",
            description="An example prompt template",
            arguments=[
                types.PromptArgument(
                    name="arg1",
                    description="Example argument",
                    required=True
                )
            ]
        )
    ]

@server.get_prompt()
async def handle_get_prompt(
    name: str,
    arguments: dict[str, str] | None
) -> types.GetPromptResult:
    if name != "example-prompt":
        raise ValueError(f"Unknown prompt: {name}")

    return types.GetPromptResult(
        description="Example prompt",
        messages=[
            types.PromptMessage(
                role="user",
                content=types.TextContent(
                    type="text",
                    text="Example prompt text"
                )
            )
        ]
    )

async def run():
    async with mcp.server.stdio.stdio_server() as (read_stream, write_stream):
        await server.run(
            read_stream,
            write_stream,
            InitializationOptions(
                server_name="example",
                server_version="0.1.0",
                capabilities=server.get_capabilities(
                    notification_options=NotificationOptions(),
                    experimental_capabilities={},
                )
            )
        )

if __name__ == "__main__":
    import asyncio
    asyncio.run(run())
```

## Writing MCP Clients

The SDK provides a high-level client interface for connecting to MCP servers:

```python
from mcp import ClientSession, StdioServerParameters
from mcp.client.stdio import stdio_client

# Create server parameters for stdio connection
server_params = StdioServerParameters(
    command="python", # Executable
    args=["example_server.py"], # Optional command line arguments
    env=None # Optional environment variables
)

async def run():
    async with stdio_client(server_params) as (read, write):
        async with ClientSession(read, write) as session:
            # Initialize the connection
            await session.initialize()

            # List available prompts
            prompts = await session.list_prompts()

            # Get a prompt
            prompt = await session.get_prompt("example-prompt", arguments={"arg1": "value"})

            # List available resources
            resources = await session.list_resources()

            # List available tools
            tools = await session.list_tools()

            # Read a resource
            resource = await session.read_resource("file://some/path")

            # Call a tool
            result = await session.call_tool("tool-name", arguments={"arg1": "value"})

if __name__ == "__main__":
    import asyncio
    asyncio.run(run())
```

## MCP Primitives

The MCP protocol defines three core primitives that servers can implement:

| Primitive | Control               | Description                                         | Example Use                  |
|-----------|-----------------------|-----------------------------------------------------|------------------------------|
| Prompts   | User-controlled       | Interactive templates invoked by user choice        | Slash commands, menu options |
| Resources | Application-controlled| Contextual data managed by the client application   | File contents, API responses |
| Tools     | Model-controlled      | Functions exposed to the LLM to take actions        | API calls, data updates      |

### Server Capabilities

MCP servers declare capabilities during initialization:

| Capability  | Feature Flag                 | Description                        |
|-------------|------------------------------|------------------------------------|
| `prompts`   | `listChanged`                | Prompt template management         |
| `resources` | `subscribe`<br/>`listChanged`| Resource exposure and updates      |
| `tools`     | `listChanged`                | Tool discovery and execution       |
| `logging`   | -                            | Server logging configuration       |
| `completion`| -                            | Argument completion suggestions    |

## Documentation

- [Model Context Protocol documentation](https://modelcontextprotocol.io)
- [Model Context Protocol specification](https://spec.modelcontextprotocol.io)
- [Officially supported servers](https://github.com/modelcontextprotocol/servers)

## Contributing

We are passionate about supporting contributors of all levels of experience and would love to see you get involved in the project. See the [contributing guide](CONTRIBUTING.md) to get started.

## License

This project is licensed under the MIT License - see the LICENSE file for details.