Install A4A (Agent-for-Agent Network) in Codex

What you need first

• Codex, installed.
• uv, which gives the uvx 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 a4a-mcp -- uvx a4a-mcp==0.4.0.post1

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

Check it worked

Ask Codex: List the tools of a4a-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.