Install Legion in Codex

What you need first

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

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 legion --env MCP_TRANSPORT=YOUR_MCP_TRANSPORT --env ALLOW_NO_MODELS=YOUR_ALLOW_NO_MODELS -- npx -y [email protected]

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

Check it worked

Ask Codex: List the tools of legion.

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.