This server provides a Model Context Protocol (MCP) implementation for executing Python code in a sandboxed environment. It uses Pyodide in Deno, ensuring the code runs in isolation from your operating system for security.
To run the MCP Python server, you'll need Deno installed on your system. The server executes Python code through Pyodide which runs in a Deno environment.
You can run the server using Deno with the following command:
deno run \
-N -R=node_modules -W=node_modules --node-modules-dir=auto \
jsr:@pydantic/mcp-run-python [stdio|sse|warmup]
The command options are:
-N -R=node_modules -W=node_modules
: Allows network access and read/write access to the ./node_modules
directory--node-modules-dir=auto
: Instructs Deno to use a local node_modules
directorystdio
: Uses the Stdio MCP transport (for running as a subprocess locally)sse
: Uses the SSE MCP transport (runs an HTTP server for local or remote connections)warmup
: Downloads and caches the Python standard library (useful for testing)Here's an example of how to use the MCP Python server with Pydantic AI:
from pydantic_ai import Agent
from pydantic_ai.mcp import MCPServerStdio
import logfire
logfire.configure()
logfire.instrument_mcp()
logfire.instrument_pydantic_ai()
server = MCPServerStdio('deno',
args=[
'run',
'-N',
'-R=node_modules',
'-W=node_modules',
'--node-modules-dir=auto',
'jsr:@pydantic/mcp-run-python',
'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.
if __name__ == '__main__':
import asyncio
asyncio.run(main())
This example demonstrates:
For complete documentation, visit https://ai.pydantic.dev/mcp/run-python/
To add this MCP server to Claude Code, run this command in your terminal:
claude mcp add-json "mcp-run-python" '{"command":"deno","args":["run","-N","-R=node_modules","-W=node_modules","--node-modules-dir=auto","jsr:@pydantic/mcp-run-python","stdio"]}'
See the official Claude Code MCP documentation for more details.
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.
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-run-python": {
"command": "deno",
"args": [
"run",
"-N",
"-R=node_modules",
"-W=node_modules",
"--node-modules-dir=auto",
"jsr:@pydantic/mcp-run-python",
"stdio"
]
}
}
}
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.
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.
To add this MCP server to Claude Desktop:
1. Find your configuration file:
~/Library/Application Support/Claude/claude_desktop_config.json
%APPDATA%\Claude\claude_desktop_config.json
~/.config/Claude/claude_desktop_config.json
2. Add this to your configuration file:
{
"mcpServers": {
"mcp-run-python": {
"command": "deno",
"args": [
"run",
"-N",
"-R=node_modules",
"-W=node_modules",
"--node-modules-dir=auto",
"jsr:@pydantic/mcp-run-python",
"stdio"
]
}
}
}
3. Restart Claude Desktop for the changes to take effect