Install Hamilton Harness in Codex

What you need first

• Codex, installed.
• Node.js, which gives the npx command the server starts with.
• Your own values for YOUR_HAMILTON_URL,YOUR_HAMILTON_ADMIN_TOKEN.

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 hamilton-harness --env HAMILTON_URL=YOUR_HAMILTON_URL --env HAMILTON_ADMIN_TOKEN=YOUR_HAMILTON_ADMIN_TOKEN -- npx -y [email protected] mcp

2. Replace YOUR_HAMILTON_URL,YOUR_HAMILTON_ADMIN_TOKEN with your own values.
3. Start Codex again and type /mcp: the server is listed.

Check it worked

Ask Codex: List the tools of hamilton-harness.

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.

The server starts, but its tools fail

A YOUR_… placeholder is still in the config, or its value is wrong.