MCP Run Python

<div align="center"> <h1>MCP Run Python</h1> </div> <div align="center"> <a href="https://github.com/pydantic/mcp-run-python/actions/workflows/ci.yml?query=branch%3Amain"><img src="https://github.com/pydantic/mcp-run-python/actions/workflows/ci.yml/badge.svg?event=push" alt="CI"></a> <a href="https://pypi.python.org/pypi/mcp-run-python"><img src="https://img.shields.io/pypi/v/mcp-run-python.svg" alt="PyPI"></a> <a href="https://github.com/pydantic/mcp-run-python"><img src="https://img.shields.io/pypi/pyversions/mcp-run-python.svg" alt="versions"></a> <a href="https://github.com/pydantic/mcp-run-python/blob/main/LICENSE"><img src="https://img.shields.io/github/license/pydantic/mcp-run-python.svg" alt="license"></a> <a href="https://logfire.pydantic.dev/docs/join-slack/"><img src="https://img.shields.io/badge/Slack-Join%20Slack-4A154B?logo=slack" alt="Join Slack" /></a> </div> <br/> <div align="center"> MCP server to run Python code in a sandbox. </div> <br/>

Code is executed using Pyodide in Deno and is therefore isolated from the rest of the operating system.

Features

• Secure Execution: Run Python code in a sandboxed WebAssembly environment
• Package Management: Automatically detects and installs required dependencies
• Complete Results: Captures standard output, standard error, and return values
• Asynchronous Support: Runs async code properly
• Error Handling: Provides detailed error reports for debugging

Usage

To use this server, you must have both Python and Deno installed.

The server can be run with deno installed using uvx:

uvx mcp-run-python [stdio|streamable-http|warmup]

where:

• stdio runs the server with the Stdio MCP transport — suitable for running the process as a subprocess locally
• streamable-http runs the server with the Streamable HTTP MCP transport - suitable for running the server as an HTTP server to connect locally or remotely. This supports stateful requests, but does not require the client to hold a stateful connection like SSE
• warmup will run a minimal Python script to download and cache the Python standard library. This is also useful to check the server is running correctly.

Usage in codes

pip install mcp-run-python
# or
uv add mcp-run-python

Then you can use mcp-run-python with Pydantic AI:

from pydantic_ai import Agent
from pydantic_ai.mcp import MCPServerStdio
from mcp_run_python import deno_args

import logfire

logfire.configure()
logfire.instrument_mcp()
logfire.instrument_pydantic_ai()

server = MCPServerStdio('deno', args=deno_args('stdio'))
agent = Agent('claude-3-5-haiku-latest', toolsets=[server])


async def main():
    async with agent:
        result = await agent.run('How many days between 2000-01-01 and 2025-03-18?')
    print(result.output)
    #> There are 9,208 days between January 1, 2000, and March 18, 2025.w

if __name__ == '__main__':
    import asyncio
    asyncio.run(main())

Logging

MCP Run Python supports emitting stdout and stderr from the python execution as MCP logging messages.

For logs to be emitted you must set the logging level when connecting to the server. By default, the log level is set to the highest level, emergency.

Currently, it's not possible to demonstrate this due to a bug in the Python MCP Client, see modelcontextprotocol/python-sdk#201.