Install @havahr/mcp-calculators in Codex

What you need first

• Codex, installed.
• Node.js, which gives the npx command the server starts with.

Steps

1. Run this in a terminal. It writes the server into ~/.codex/config.toml, which the Codex CLI, its IDE extension and the ChatGPT desktop app share.

codex mcp add hava4-mcp-calculators -- npx -y @havahr/mcp-calculators

2. Start Codex again and type /mcp: the server is listed.

Check it worked

Ask Codex: List the tools of hava4-mcp-calculators.

If it does not start

spawn npx ENOENT

Node.js is not on the PATH that Codex sees. Install it, or write the full path of npx in the config.