Pyodide Integration MCP server

The mcp-pyodide server provides Python code execution capabilities for Large Language Models (LLMs) through the Model Context Protocol (MCP) interface. Built with TypeScript, it enables LLMs to run Python code using Pyodide as the execution environment.

Installation

Install the package from npm:

npm install mcp-pyodide

Basic Usage

Using as a Server in Your Code

Import and run the server in your TypeScript/JavaScript application:

import { runServer } from "mcp-pyodide";

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

Using as a Command-line Tool

Start the server in stdio mode (default):

mcp-pyodide

Start in Server-Sent Events (SSE) mode:

mcp-pyodide --sse

Transport Modes

Standard I/O Mode

This is the default mode where the server communicates through standard input and output.

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

Here's an example of how to connect a client to the SSE server:

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

Configuration Options

Environment Variables

You can customize the server behavior with these 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)

System Requirements

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

Security Considerations

Exercise caution when executing untrusted code. The server provides Python execution capabilities, which could potentially be misused if proper safeguards are not in place.

When using SSE mode, ensure proper CORS configuration if needed, especially when integrating with web applications across different domains.

How to install this MCP server

For Claude Code

To add this MCP server to Claude Code, run this command in your terminal:

claude mcp add-json "mcp-pyodide" '{"command":"npx","args":["-y","mcp-pyodide"]}'

See the official Claude Code MCP documentation for more details.

For Cursor

There are two ways to add an MCP server to Cursor. The most common way is to add the server globally in the ~/.cursor/mcp.json file so that it is available in all of your projects.

If you only need the server in a single project, you can add it to the project instead by creating or adding it to the .cursor/mcp.json file.

Adding an MCP server to Cursor globally

To add a global MCP server go to Cursor Settings > Tools & Integrations and click "New MCP Server".

When you click that button the ~/.cursor/mcp.json file will be opened and you can add your server like this:

{
    "mcpServers": {
        "mcp-pyodide": {
            "command": "npx",
            "args": [
                "-y",
                "mcp-pyodide"
            ]
        }
    }
}

Adding an MCP server to a project

To add an MCP server to a project you can create a new .cursor/mcp.json file or add it to the existing one. This will look exactly the same as the global MCP server example above.

How to use the MCP server

Once the server is installed, you might need to head back to Settings > MCP and click the refresh button.

The Cursor agent will then be able to see the available tools the added MCP server has available and will call them when it needs to.

You can also explicitly ask the agent to use the tool by mentioning the tool name and describing what the function does.

For Claude Desktop

To add this MCP server to Claude Desktop:

1. Find your configuration file:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json
• Linux: ~/.config/Claude/claude_desktop_config.json

2. Add this to your configuration file:

{
    "mcpServers": {
        "mcp-pyodide": {
            "command": "npx",
            "args": [
                "-y",
                "mcp-pyodide"
            ]
        }
    }
}

3. Restart Claude Desktop for the changes to take effect