Codex

codex mcp add rho --url https://api.rho.store/mcp
codex mcp login rho

The login opens rho in your browser: sign in, choose Read and write or Read only, and allow it.

codex mcp add writes rho into ~/.codex/config.toml. You can write it there yourself instead:

[mcp_servers.rho]
url = "https://api.rho.store/mcp"

In a Codex session, /mcp lists the servers it has.