A Codex plugin in the portable Agent Plugins format. It registers the Phoenix remote MCP server so Codex can explore traces, sessions, datasets, experiments, and evaluations in your Phoenix instance.
Plugin MCP URLs cannot contain environment variables, so the plugin registers a small stdio launcher, scripts/phoenix-mcp, instead of a fixed URL. The launcher reads your environment and bridges to <PHOENIX_ENDPOINT>/mcp with mcp-remote via npx.
| Variable | Effect |
|---|---|
PHOENIX_ENDPOINT |
Base URL of your Phoenix instance, for example https://phoenix.example.com. Defaults to http://localhost:6006. |
PHOENIX_API_KEY |
Optional. When set, requests carry it as a bearer token and no browser login is needed. The launcher passes mcp-remote an unexpanded ${PHOENIX_API_KEY} reference that it resolves from its environment, so the key never appears in the process arguments. Otherwise Codex opens a browser window to sign in with your Phoenix account on first use. |
These are the same variables the px CLI reads. Export them in the shell you launch Codex from. Codex forwards only the variables the plugin declares, which is why both are listed in mcp.json and .mcp.json.
Requires Node.js, and Phoenix 19.0.0 or later, which serves /mcp.
| File | Purpose |
|---|---|
plugin.json, mcp.json |
Portable manifest and MCP server declaration. |
.codex-plugin/plugin.json, .mcp.json |
Codex overlay that turns the ${VAR} entries in mcp.json into forwarded environment variables. Codex reads the portable files first; the overlay only adds env_vars. |
scripts/phoenix-mcp |
The stdio launcher. |
From the repository root:
codex plugin marketplace add .
codex plugin add arize-phoenix@arize-phoenixRun /mcp inside Codex to confirm the phoenix server is connected.