Codex

OpenAI Codex manages MCP servers through the codex mcp CLI. See the MCP server reference for the full tool list and response shapes.

Install the server

Make sure the plumb binary is on your PATH. If you installed via cargo install plumb-cli, it should already be available.

Register the server

Add Plumb as an MCP server:

codex mcp add plumb -- plumb mcp

For a source checkout (useful when hacking on Plumb itself):

codex mcp add plumb -- cargo run --quiet -p plumb-cli -- mcp

Confirm the registration:

codex mcp list

You should see plumb in the output.

Verify the connection

Start a new Codex session in the project directory. Codex picks up the registered server and makes its tools available.

Test the transport:

Use plumb’s echo tool to send “hello”.

Lint a page

Ask Codex:

Use plumb to lint https://example.com

Codex calls lint_url and returns the violation summary.

Common issues

PATH resolution, working directory, large responses, and sandboxed network access apply to every agent integration. See Common issues for the consolidated list.

The Codex-specific note: register the server with an absolute path when the sandbox PATH does not include plumb:

codex mcp add plumb -- /home/you/.cargo/bin/plumb mcp

Codex sandboxes may also block outbound network. Use plumb-fake://hello to verify the tool chain without granting network access; only lint_url against a real host needs the network allowance.

See also

• MCP server reference — tool list, response shapes, resource URIs.
• Configuration — plumb.toml reference.
• Install — binary installation options.