Why is MCP Python Interpreter not working in Cursor?

It failed in our test on Oct 15, 2026. Errors we observed: no successful call to this server's tools; answer missing ['42']; no tool result containing ['42']

MCP Python Interpreter not working in Cursor? Fixes

Failed It failed in our test on Oct 15, 2026. Below is the exact setup we used in Cursor (2026.10.14-941492e), every error we saw, and what to check, all from our own run log.

Date tested: Oct 15, 2026 · From our harness, not the maker’s claims · How we test

1. Use the install config we tested in Cursor

{
 "mcpServers": {
  "mcp-python-interpreter": {
   "command": "uvx",
   "args": [
    "mcp-python-interpreter",
    "--dir",
    "/workspace/timmy/harness/sandbox/pyinterp"
   ]
  }
 }
}

Replace any <YOUR_…> placeholder and local test paths with your own. Every client’s tested snippet is on the MCP Python Interpreter page.

2. Check that Cursor connects to it

In our run the connect check was failed. Our check output:

mcp-python-interpreter: Error: Connection failed

Errors we observed

agent task: run cell: no successful call to this server's tools; answer missing ['42']; no tool result containing ['42']

Quoted from our run log. Secrets redacted. We list only what we saw.

More help

MCP Python Interpreter: all results and setup · Full Cursor run · General Cursor MCP troubleshooting