Arize Phoenix MCP Server

npx -y @arizeai/phoenix-mcp@latest --baseUrl https://my-phoenix.com --apiKey YOUR_KEY

{
  "mcpServers": {
    "arize-phoenix-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "@arizeai/phoenix-mcp@latest",
        "--baseUrl",
        "https://my-phoenix.com",
        "--apiKey",
        "YOUR_KEY"
      ]
    }
  }
}

Phoenix is Arize's open-source observability and evaluation platform, and this package exposes it over MCP so the debugging loop happens where the code is being written. Reads cover projects, traces, spans, annotation configs and session-level conversation flows, plus datasets and the results of experiments. The part that changes how it is used is that prompts are writable, not just readable: the agent can list, create, update and iterate the prompt versions Phoenix stores, so a prompt edit and the experiment that measures it sit inside one conversation instead of two tools. Connection is two command-line arguments, baseUrl and apiKey, which means a self-hosted Phoenix on localhost:6006 and a hosted instance are wired up identically.