Install Subagent MCP 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 subagent-mcp -- uvx subagent-harness-mcp==1.0.31 serve

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

Check it worked

Ask Codex: List the tools of subagent-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.