Connect Your Coding Agent

Works with Claude Code, Codex, Cursor, or any other coding agent. Once connected, you ask in plain language:

Show me the latest traces in my default project and summarize any errors

Connect your agent

Each agent has one recommended setup. Every setup connects the agent to the MCP server built into Phoenix, which gives it your Phoenix data and the Phoenix skills.

Agent	Recommended setup
Claude Code	Install the Claude Code plugin.
Codex	Install the Codex plugin.
Cursor	Add the MCP server. On a Teams or Enterprise plan, an admin can add the Cursor plugin to a team marketplace instead.
VS Code, Gemini CLI, OpenCode, Claude Desktop, and other MCP clients	Add the MCP server with your client’s steps.
An agent with no MCP support	Install the Phoenix CLI and its skill: `npx skills add Arize-ai/phoenix --skill phoenix-cli`.

Then ask your agent a question, such as List my Phoenix projects. You don’t need the CLI when your agent has the MCP server. Add it if you also want the agent to run px commands in a terminal, where you can see and rerun each one. See CLI or MCP server?

Example prompts

Instrument an app:

Use the Phoenix tracing skill to instrument this application. First inspect the codebase and identify the LLM providers, frameworks, package manager, and existing OpenTelemetry setup. Then propose the Phoenix instrumentation plan before changing code.

Run the Evaluate flow end to end:

Download https://storage.googleapis.com/arize-phoenix-assets/assets/images/arize-docs-images/evaluate/travel-support.csv and create a Phoenix dataset called "travel-support" from it, mapping the question column to input and expected_answer to output. Then write an LLM-as-a-judge evaluator that scores whether a reply answers the question and matches the expected answer. Run an experiment over the dataset with a travel support prompt, and tell me which examples scored lowest and why.

Every example scores 0 on that first run: the prompt knows nothing about this airline. Then reply Add the Basic fare policy to the prompt, rerun the experiment, and compare the scores.

Find your Phoenix endpoint

Every setup needs your Phoenix endpoint: the base URL you open Phoenix at, with no trailing slash or path.

Deployment	Endpoint	MCP server URL the tools derive from it
Local Phoenix (`phoenix serve`)	`http://localhost:6006`	`http://localhost:6006/mcp`
Deployed Phoenix	`https://phoenix.example.com` (your deployment’s hostname)	`https://phoenix.example.com/mcp`

The plugins and px append /mcp themselves; only hand-written MCP config takes the full /mcp URL. The Codex plugin and px read it from your shell:

export PHOENIX_ENDPOINT=http://localhost:6006    # Your Phoenix endpoint
export PHOENIX_PROJECT=my-project                # Project name
export PHOENIX_API_KEY=your-api-key              # API key (if auth enabled)

Plugins

Each plugin registers the Phoenix MCP server and installs all five Phoenix skills as files, in one install that updates with the plugin. The plugins need Phoenix 19.0.0 or later.

Claude Code plugin

Steps 1, 2, and 4 are slash commands inside a Claude Code session. If /plugin is not recognized, update Claude Code.

Add the marketplace

/plugin marketplace add Arize-ai/phoenix

Install the plugin

/plugin install arize-phoenix@arize-phoenix

Claude Code asks for a scope: user for all your projects, project to share it with collaborators through .claude/settings.json, or local for this repository only.

Set your Phoenix endpoint

Claude Code prompts for one setting, Phoenix endpoint, as it enables the plugin. Enter your Phoenix endpoint, or keep the default http://localhost:6006. The plugin appends /mcp itself, so a trailing slash or a pasted /mcp produces a wrong URL (…//mcp or …/mcp/mcp). This setting is stored in your user settings and applies to every project.

Verify

Run /mcp and select phoenix. If your Phoenix has auth enabled, a browser window opens to sign in with your Phoenix account; without auth, it connects straight away.claude plugin details arize-phoenix@arize-phoenix lists what it added.

From a shell: claude plugin marketplace add Arize-ai/phoenix then claude plugin install arize-phoenix@arize-phoenix (add --scope project or --scope local to narrow it).What it registers

Component	What it is
`phoenix` MCP server	Streamable HTTP to `<your-endpoint>/mcp`, the Remote MCP Server.
Five skills	`phoenix-cli`, `phoenix-error-analysis`, `phoenix-evals`, `phoenix-harbor`, and `phoenix-tracing`. See Skills.

The phoenix-cli skill runs the optional px CLI. The plugin doesn’t install px. To use that skill, install the CLI.Change the endpoint. claude plugin install arize-phoenix@arize-phoenix --config endpoint=https://phoenix.example.com at install time, /plugin configure afterward, or edit ~/.claude/settings.json:

{
  "pluginConfigs": {
    "arize-phoenix@arize-phoenix": {
      "options": { "endpoint": "https://phoenix.example.com" }
    }
  }
}

Authentication. With auth on, the first use opens a browser sign-in. For headless use, register the server by hand with an API key instead.Update or remove

claude plugin update arize-phoenix@arize-phoenix     # pull the latest version
claude plugin disable arize-phoenix@arize-phoenix    # keep it installed, turn it off
claude plugin uninstall arize-phoenix@arize-phoenix  # remove the plugin

Pass the scope you installed at, such as --scope local, to disable and uninstall.

Codex plugin

Registers the phoenix MCP server and installs the five Phoenix skills.Prerequisites: Phoenix 19.0.0 or later, and Node.js. The plugin starts its MCP bridge with npx. The codex plugin commands below run in your shell.

Add the marketplace

codex plugin marketplace add Arize-ai/phoenix

Codex clones the repository and reads the catalog from .agents/plugins/marketplace.json. The source can be owner/repo shorthand, owner/repo@ref, an HTTPS or SSH Git URL, or a local path; pass --ref to pin a Git ref.

Install the plugin

codex plugin add arize-phoenix@arize-phoenix

Codex caches the plugin under ~/.codex/plugins/cache/arize-phoenix/arize-phoenix/<version> and enables it in ~/.codex/config.toml. You can also browse and install from the /plugins browser inside Codex.

Export your Phoenix endpoint

The plugin reads PHOENIX_ENDPOINT from the shell you launch Codex from:

export PHOENIX_ENDPOINT=https://phoenix.example.com   # base URL only; the plugin appends /mcp
export PHOENIX_API_KEY=your-api-key                   # only if auth is enabled

Unset, it defaults to http://localhost:6006.

Verify

codex mcp list

The phoenix server appears as enabled. Then launch codex and run /mcp to confirm it connects. If your Phoenix has auth enabled and PHOENIX_API_KEY is not set, a browser window opens on first use to sign in; with the key set, or with auth disabled, no login happens.

Variable	Effect
`PHOENIX_ENDPOINT`	Base URL; `/mcp` is appended for you.
`PHOENIX_API_KEY`	Optional. Sent as a bearer token, so no browser login.

Disable or remove. In ~/.codex/config.toml:

[plugins."arize-phoenix@arize-phoenix"]
enabled = true

codex plugin marketplace upgrade arize-phoenix   # refresh the catalog snapshot
codex plugin remove arize-phoenix@arize-phoenix  # uninstall and clear the cache
codex plugin marketplace remove arize-phoenix    # drop the marketplace

Cursor plugin

The Cursor plugin isn’t in Cursor’s public marketplace. On a Teams or Enterprise plan, an admin adds it to a team marketplace. Otherwise, add the MCP server by hand. It serves four of the five skills.

Add the plugin to a team marketplace

In the Cursor dashboard, an admin opens Plugins & MCPs, then Team Marketplaces, selects Add Marketplace, and imports the repository https://github.com/Arize-ai/phoenix.

Set your Phoenix endpoint

Set the plugin’s Phoenix endpoint variable to your Phoenix endpoint, or keep the default http://localhost:6006. On a team marketplace, the admin sets it once for everyone. The plugin appends /mcp.

Install the plugin

In Cursor, open Customize in the sidebar, find Arize Phoenix, and select Install.

Verify

Use a Phoenix MCP tool once, for example by asking List my Phoenix projects. If your Phoenix has auth enabled, a browser window opens to sign in.

What it registers

Component	What it is
`phoenix` MCP server	Streamable HTTP to `<your-endpoint>/mcp`, the Remote MCP Server.
`phoenix-docs` MCP server	Search over the Phoenix docs. See Phoenix Docs MCP.
Five skills	`phoenix-cli`, `phoenix-error-analysis`, `phoenix-evals`, `phoenix-harbor`, and `phoenix-tracing`.

Authentication. The plugin signs in through the browser and has no setting for an API key. For headless use, add the server by hand with an API key instead.Already added the servers by hand? The plugin uses the same server names, phoenix and phoenix-docs. Remove your entries from ~/.cursor/mcp.json or .cursor/mcp.json so each server appears once.To install the plugin from a local checkout, see the Cursor plugin README.

Learn more

Tracing coding agents: have Phoenix record your coding agent’s own turns, tool calls, and token costs.

Tracing

Evaluation

Datasets & Experiments

Prompts

Settings

Concepts

Resources

Connect Your Coding Agent

Connect your agent

Example prompts

Find your Phoenix endpoint

Plugins

Learn more

​Connect your agent

​Example prompts

​Find your Phoenix endpoint

​Plugins

​Learn more

Connect your agent

Example prompts

Find your Phoenix endpoint

Plugins

Learn more