Install Arachne in Codex

What you need first

• Codex, installed.
• uv, which gives the uvx command the server starts with.
• Your own value for YOUR_ARACHNE_API_KEY.

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 arachne-mcp --env ARACHNE_API_KEY=YOUR_ARACHNE_API_KEY -- uvx arachne-mcp==1.4.0

2. Replace YOUR_ARACHNE_API_KEY with your own value.
3. Start Codex again and type /mcp: the server is listed.

Check it worked

Ask Codex: List the tools of arachne-mcp.

If it does not start

spawn uvx ENOENT

uv is not on the PATH that Codex sees. Install it, or write the full path of uvx in the config.

The server starts, but its tools fail

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