MCP Python SDK 🔌 MCP server Open source

What it does

This is the official Python SDK for the Model Context Protocol, maintained by the MCP project. It lets you build MCP servers that expose tools, resources and prompts to any MCP host, and MCP clients that connect to any server. The same package does both. Servers are written as plain type-hinted Python functions: the type hints become the schema, so you do not write JSON Schema, request parsing or validation by hand. It speaks every standard transport, meaning stdio, Streamable HTTP and SSE. The current release line is v2, reworked for the latest protocol revision, with v1 still maintained on its own branch.

Tools it gives your agent

This is a development library, not a ready-to-run server, so it does not hand your agent a fixed set of tools. Instead you use it to define your own: decorate a function with @mcp.tool() to expose a tool, or @mcp.resource(...) to expose a resource, and the SDK handles the protocol. The cli extra adds an mcp command with mcp dev, mcp run and mcp install for testing a server in the MCP Inspector.

Works with

Any MCP host or client, since it implements the protocol both sides use. Requires Python 3.10 or newer.

How to install

uv add "mcp[cli]"      # or: pip install "mcp[cli]"

Maintenance and safety

The SDK is MIT-licensed and very actively maintained, and it is the reference Python implementation of MCP. Because v2 is a major rework, pin an upper bound such as mcp>=1.28,<2 until you have migrated, since pip install mcp now installs 2.x. A server you build with it runs with whatever access your code gives it, so apply the usual care with tools that touch the filesystem, the network or credentials.

Who should use it

It suits developers who want to build MCP servers or clients in Python and prefer to write ordinary functions rather than protocol plumbing. It is the natural starting point for exposing your own data or tools to coding agents.