evals

Go from zero to your first Arize AX traces in one command. evals launches your coding agent, seeded with a guided onboarding prompt that walks you through signing up, adding tracing, and confirming traces land — for your app, or for the coding agent itself.

Quick start

npx evals

You'll see a picker of the coding agents installed on your machine (Claude Code, Codex, Cursor, GitHub Copilot, Antigravity CLI). Pick one and it launches in your current directory, seeded with the onboarding prompt — so run npx evals from the project you want to instrument.

Pasted npx evals into a coding agent? If an agent runs it as a shell command there is no interactive terminal, so nothing is launched. It stages the onboarding prompt and prints two lines asking you to re-run in a terminal, with the staged prompt path in case you would rather point your agent at it yourself. Agents treat command output as data rather than instructions, so this deliberately asks you rather than trying to hand the flow to them.

No coding agent installed? The picker shows install links instead.

Needs Node.js 20 or newer (the Ink UI does). On anything older, npx evals says so and points you at the shell launcher below rather than failing obscurely.

Without Node

If you don't have Node — or have one older than 20 — use the shell launchers (they detect an agent and fetch the prompt from this published package via jsDelivr):

# macOS / Linux
bash <(curl -fsSL https://cdn.jsdelivr.net/npm/evals/start.sh)

# Windows (PowerShell)
irm https://cdn.jsdelivr.net/npm/evals/start.ps1 | iex

When Node 20+ is present, these hand off to npx evals for the richer UI. On an older Node they say so and carry on in the shell, which needs no Node at all.

What it does

1. Detects an installed coding agent (never executes it — just a PATH lookup).
2. Launches the agent in your current directory, seeded with the bundled onboarding prompt (onboarding-prompt.md).
3. The agent walks you through: create/sign in to Arize AX → pick what to trace → instrument it → verify your first traces.

You can trace an existing app (the one in the current folder, or another one you point it at by path), a starter app the agent creates, or the coding agent itself — so every session you run, in any project, shows up in Arize AX. Agent tracing is machine-wide and captures prompts and tool output by default, so the prompt asks for that explicitly and offers per-category opt-outs.

The agent runs with its normal permission model — evals never passes skip-permissions, so you approve each step, and the prompt itself gates real changes on your confirmation.

Options

| Variable | Applies to | Effect | |----------|-----------|--------| | ARIZE_AGENT=<id> | start.sh / start.ps1 | Skip the picker and use this agent (claude, codex, cursor-agent, copilot, agy). | | ARIZE_SKIP_NPX=1 | start.sh / start.ps1 | Force the shell path even when Node/npx is available. | | ARIZE_PROMPT_URL=<url> | start.sh / start.ps1 | Fetch the onboarding prompt from a custom URL (supports file://). | | ARIZE_ONBOARDING_DIR=<dir> | all three | Stage the prompt somewhere other than ~/.arize/onboarding. |

The shell launchers also accept --agent <id>.

The prompt is staged in ~/.arize/onboarding and handed to your agent by path, since it's too large to pass as a command-line argument. That directory is cleared at the start of each launch and holds nothing but the prompt and the offline tracing bundle. If your home directory isn't writable, the launcher says so and falls back to a temp directory — instrumenting an app still works, but tracing the coding agent itself needs a writable home.

About Arize

Arize AX is the AI engineering platform for tracing, evaluating, and observing LLM and agent applications. Learn more at arize.com.

Contributing

Development setup and the release process live in CONTRIBUTING.md.