diff --git a/README.en.md b/README.en.md new file mode 100644 index 0000000..3822976 --- /dev/null +++ b/README.en.md @@ -0,0 +1,129 @@ +# MCP Python SDK + +
+ +Python implementation of the Model Context Protocol (MCP) + +[![PyPI][pypi-badge]][pypi-url] +[![MIT licensed][mit-badge]][mit-url] +[![Python Version][python-badge]][python-url] +[![Documentation][docs-badge]][docs-url] +[![Protocol][protocol-badge]][protocol-url] +[![Specification][spec-badge]][spec-url] + +
+ +> [!CAUTION] +> **This README documents v2 of the MCP Python SDK — a pre-release (alpha/beta) line under active development. Do not use v2 in production.** Pre-releases are published to PyPI as `2.0.0aN` / `2.0.0bN`, and **each pre-release may contain breaking changes from the previous one**. Pin an exact version and expect to update your code when you bump the pin. +> +> **v1.x is the only stable release line and remains recommended for production.** It lives on the [`v1.x` branch](https://github.com/modelcontextprotocol/python-sdk/tree/v1.x) and continues to receive critical bug fixes and security patches; see [the v1.x README](https://github.com/modelcontextprotocol/python-sdk/blob/v1.x/README.md) for its documentation. `pip` and `uv` don't select a pre-release unless you explicitly request one, so existing installs are unaffected. **If your package depends on `mcp`, add a `<2` upper bound to your version constraint (for example `mcp>=1.27,<2`) before the stable release lands.** +> +> v2 is a major rework of the SDK, both to support the [2026-07-28 MCP specification release](https://blog.modelcontextprotocol.io/posts/2026-07-28-release-candidate/) and to fix long-standing architectural issues. See [What's new in v2](https://py.sdk.modelcontextprotocol.io/v2/whats-new/) for the tour of what changed, and the [migration guide](https://py.sdk.modelcontextprotocol.io/v2/migration/) for every breaking change. Stable v2 is targeted for 2026-07-27, alongside the spec release. Try the pre-releases and [tell us what breaks](https://github.com/modelcontextprotocol/python-sdk/issues/new?template=v2-feedback.yaml), or discuss in [#python-sdk-dev on the MCP Contributors Discord](https://discord.gg/6CSzBmMkjX). + +## Documentation + +**The documentation lives at .** + +It has a [Get started guide](https://py.sdk.modelcontextprotocol.io/v2/get-started/), [What's new in v2](https://py.sdk.modelcontextprotocol.io/v2/whats-new/), the [API reference](https://py.sdk.modelcontextprotocol.io/v2/api/mcp/), and the [migration guide](https://py.sdk.modelcontextprotocol.io/v2/migration/). + +## What is MCP? + +The [Model Context Protocol](https://modelcontextprotocol.io) lets you build servers that expose data and functionality to LLM applications in a secure, standardized way. Think of it like a web API, but designed for LLM interactions. With this SDK you can: + +- **Build MCP servers** that expose tools, resources, and prompts to any MCP host +- **Build MCP clients** that connect to any MCP server +- Speak every standard transport: stdio, Streamable HTTP, and SSE + +## Requirements + +Python 3.10+. + +## Installation + +```bash +uv add "mcp[cli]==2.0.0b1" # or: pip install "mcp[cli]==2.0.0b1" +``` + +The pin matters while v2 is in pre-release: an unpinned install resolves to the latest stable v1.x, which this README does not describe. Check [PyPI](https://pypi.org/project/mcp/#history) for the newest pre-release, and use `uv run --with "mcp==2.0.0b1"` for one-off commands. + +## A server in 15 lines + +Create a `server.py`: + + +```python +from mcp.server import MCPServer + +mcp = MCPServer("Demo") + + +@mcp.tool() +def add(a: int, b: int) -> int: + """Add two numbers.""" + return a + b + + +@mcp.resource("greeting://{name}") +def greeting(name: str) -> str: + """Greet someone by name.""" + return f"Hello, {name}!" +``` + +_Full example: [docs_src/index/tutorial001.py](https://github.com/modelcontextprotocol/python-sdk/blob/main/docs_src/index/tutorial001.py)_ + + +That's a complete MCP server: one tool, one templated resource. Open it in the [MCP Inspector](https://github.com/modelcontextprotocol/inspector): + +```bash +uv run mcp dev server.py +``` + +Call `add` with `a=1`, `b=2` and you get `3` back. + +Notice what you did **not** write: no JSON Schema (`a: int, b: int` _is_ the schema), no request parsing, no validation code, no protocol handling. Two type-hinted Python functions and a docstring. + +[Get started](https://py.sdk.modelcontextprotocol.io/v2/get-started/) takes it from here. + +## A client in 10 lines + +The same package is a full MCP **client**. `Client` connects to a URL, a stdio subprocess, a custom transport, or (for tests) straight to a server object in memory with no transport at all: + +```python +import asyncio + +from mcp import Client + +from server import mcp + + +async def main() -> None: + async with Client(mcp) as client: + result = await client.call_tool("add", {"a": 1, "b": 2}) + print(result.structured_content) # {'result': 3} + + +asyncio.run(main()) +``` + +Swap `mcp` for `"http://localhost:8000/mcp"` and the exact same code talks to a remote server. + +## 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](https://github.com/modelcontextprotocol/python-sdk/blob/main/CONTRIBUTING.md) to get started. + +## License + +This project is licensed under the MIT License. See the [LICENSE](https://github.com/modelcontextprotocol/python-sdk/blob/main/LICENSE) file for details. + +[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-python--sdk-blue.svg +[docs-url]: https://py.sdk.modelcontextprotocol.io/v2/ +[protocol-badge]: https://img.shields.io/badge/protocol-modelcontextprotocol.io-blue.svg +[protocol-url]: https://modelcontextprotocol.io +[spec-badge]: https://img.shields.io/badge/spec-spec.modelcontextprotocol.io-blue.svg +[spec-url]: https://modelcontextprotocol.io/specification/latest