mcp-pyodide

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A Pyodide server implementation for the Model Context Protocol (MCP). This server enables Large Language Models (LLMs) to execute Python code through the MCP interface.

Features

• Python code execution capability for LLMs using Pyodide
• MCP compliant server implementation
• Support for both stdio and SSE transport modes
• Robust implementation written in TypeScript
• Available as a command-line tool

Installation

npm install mcp-pyodide

Usage

As a Server

import { runServer } from "mcp-pyodide";
 
// Start the server
runServer().catch((error: unknown) => {
  console.error("Error starting server:", error);
  process.exit(1);
});

As a Command-line Tool

Start in stdio mode (default):

mcp-pyodide

Start in SSE mode:

mcp-pyodide --sse

SSE Mode

When running in SSE mode, the server provides the following endpoints:

• SSE Connection: http://localhost:3020/sse
• Message Handler: http://localhost:3020/messages

Example client connection:

const eventSource = new EventSource("http://localhost:3020/sse");
eventSource.onmessage = (event) => {
  console.log("Received:", JSON.parse(event.data));
};

Project Structure

mcp-pyodide/
├── src/
│   ├── formatters/    # Data formatting handlers
│   ├── handlers/      # Request handlers
│   ├── lib/          # Library code
│   ├── tools/        # Utility tools
│   ├── utils/        # Utility functions
│   └── index.ts      # Main entry point
├── build/            # Build artifacts
├── pyodide-packages/ # Pyodide-related packages
└── package.json

Dependencies

• @modelcontextprotocol/sdk: MCP SDK (^1.4.0)
• pyodide: Python runtime environment (^0.27.1)
• arktype: Type validation library (^2.0.1)
• express: Web framework for SSE support
• cors: CORS middleware for SSE support

Development

Requirements

• Node.js 18 or higher
• npm 9 or higher

Setup

# Clone the repository
git clone <repository-url>
 
# Install dependencies
npm install
 
# Build
npm run build

Scripts

• npm run build: Compile TypeScript and set execution permissions
• npm start: Run server in stdio mode
• npm run start:sse: Run server in SSE mode

Environment Variables

• PYODIDE_CACHE_DIR: Directory for Pyodide cache (default: ”./cache”)
• PYODIDE_DATA_DIR: Directory for mounted data (default: ”./data”)
• PORT: Port for SSE server (default: 3020)

License

ISC

Contributing

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -am 'Add some amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Create a Pull Request

Important Notes

• This project is under development, and the API may change
• Thoroughly test before using in production
• Exercise caution when executing untrusted code for security reasons
• When using SSE mode, ensure proper CORS configuration if needed

Support

Please use the Issue tracker for problems and questions.