NOTICE

We've decided to retire and archive this project - there's just no safe way to run Python within pyodide safely with reasonable latency.

Instead, we're working hard on Monty which should solve the usecase we initially intended for mcp-run-python, with better security, lower latency, easier install, and better ways to communicate with the OS.

If you want to use this projects code, or otherwise use pyodide to run LLM generated code, feel free to do so.

However be extremely careful about how you sandbox the service and what code you allow to run.

In particular Python code running in pyodide can run arbitrary javascript meaning it can do whatever the javascript runtime running pydodie can do, including:

• tainting that runtime to control or alter how code runs on later onvocations
• reading and/or writing to any files that runtime has access to
• OOMing the machine by consuming all memory - deno has no good way limit memory usage

These issues are not problems with Pyodide or Deno - they're behaving as advertised, it's just that those tools were not designed as sandboxes to run untrusted code.

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

(This code was previously part of Pydantic AI but was moved to a separate repo to make it easier to maintain.)

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 [-h] [--version] [--port PORT] [--deps DEPS] {stdio,streamable-http,streamable-http-stateless,example}

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
• streamable-http-stateless runs the server with Streamable HTTP MCP transport in stateless mode and does not support server-to-client notifications
• example will run a minimal Python scrip

... View full README on GitHub