Install Better Call Claude in Codex

What you need first

• Codex, installed.
• Node.js, which gives the npx command the server starts with.
• Your own values for YOUR_BETTERCALLCLAUDE_PHONE_PROVIDER,YOUR_BETTERCALLCLAUDE_PHONE_NUMBER,YOUR_BETTERCALLCLAUDE_PHONE_ACCOUNT_SID,YOUR_BETTERCALLCLAUDE_PHONE_AUTH_TOKEN,YOUR_BETTERCALLCLAUDE_USER_PHONE_NUMBER,YOUR_BETTERCALLCLAUDE_OPENAI_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 better-call-claude --env BETTERCALLCLAUDE_PHONE_PROVIDER=YOUR_BETTERCALLCLAUDE_PHONE_PROVIDER --env BETTERCALLCLAUDE_PHONE_NUMBER=YOUR_BETTERCALLCLAUDE_PHONE_NUMBER --env BETTERCALLCLAUDE_PHONE_ACCOUNT_SID=YOUR_BETTERCALLCLAUDE_PHONE_ACCOUNT_SID --env BETTERCALLCLAUDE_PHONE_AUTH_TOKEN=YOUR_BETTERCALLCLAUDE_PHONE_AUTH_TOKEN --env BETTERCALLCLAUDE_USER_PHONE_NUMBER=YOUR_BETTERCALLCLAUDE_USER_PHONE_NUMBER --env BETTERCALLCLAUDE_OPENAI_API_KEY=YOUR_BETTERCALLCLAUDE_OPENAI_API_KEY -- npx -y [email protected]

2. Replace YOUR_BETTERCALLCLAUDE_PHONE_PROVIDER,YOUR_BETTERCALLCLAUDE_PHONE_NUMBER,YOUR_BETTERCALLCLAUDE_PHONE_ACCOUNT_SID,YOUR_BETTERCALLCLAUDE_PHONE_AUTH_TOKEN,YOUR_BETTERCALLCLAUDE_USER_PHONE_NUMBER,YOUR_BETTERCALLCLAUDE_OPENAI_API_KEY with your own values.
3. Start Codex again and type /mcp: the server is listed.

Check it worked

Ask Codex: List the tools of better-call-claude.

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.