If you want to look around before instrumenting, click **Explore the platform first** at the bottom of the page. This will take you to your space home, and you can return to these steps any time from **Tracing Projects** in the sidebar.
Both send traces to the same project. Pick a path below: **`npx evals`** to have your coding agent do all of it (recommended), **Arize Skills** to drive each step from your editor yourself, or **Code** to set up the SDK directly.
When it finishes, open your project in Arize AX and expand any span tree to see the model, the prompt, the response, the latency, and the token counts. Look for a response that's wrong or incomplete, then walk its spans to see where it broke.
For the full breakdown, including the installers to use without Node.js, see [one command setup](/docs/ax/set-up-with-ai-assistants#one-command-setup).
### Step 2: Generate an API key
Click **Generate API key**. Arize AX creates a key and the step changes to **Key created** with a **Copy Key** button.
### Step 3: Set up environment variables
The page shows a `.env` block with your Space ID and OTLP endpoint already filled in and your new key masked. Copy it into your project's `.env`:
```bash theme={"theme":{"light":"github-light-default","dark":"github-dark-default"}}
ARIZE_SPACE_ID=your-space-id
ARIZE_API_KEY=your-api-key
ARIZE_OTLP_ENDPOINT=https://otlp.arize.com/v1
```
The endpoint matches the region you signed in to (`otlp.arize.com`, `otlp.eu-west-1a.arize.com`, or `otlp.ca-central-1a.arize.com`).
### Step 4: Watch for your first trace
Step 4 is a live listener labeled **Listening for traces**. Leave the page open and run your app. It shows **Processing traces** when spans start arriving, then turns green with **Traces received** and a **View Project** button.
If nothing arrives in about 45 seconds, the listener switches to **No traces yet** with **Troubleshoot** and **Reset** buttons. **Troubleshoot** expands four checks:
1. **API Key**: look for `401` or `StatusCode.INTERNAL` in your terminal.
2. **Space ID**: a mismatched ID silently routes traces to another space.
3. **Endpoint**: confirm you're using the HTTP or gRPC endpoint your transport expects.
4. **Silent failures**: `BatchSpanProcessor` swallows exporter errors, so swap in `SimpleSpanProcessor` to see them.
### See your traces in Arize AX
Export recent spans to inspect what each request did (what was retrieved, the LLM call, inputs and outputs) without leaving your editor, using the [`arize-trace`](https://github.com/Arize-ai/arize-skills/blob/main/skills/arize-trace/SKILL.md) skill. For example, you might say:
> Export the latest traces from my project and summarize what each request did and how it answered
The same traces also appear under your project in Arize AX, where you can expand any span tree to see the model, prompt, response, latency, and token counts.
Click on any trace to expand it. You'll see the full span tree:
* **The LLM span**: the model called, the messages sent, the response, the latency, and the token counts
* **Input and output**: the exact prompt sent (including any context passed to the model) and the response returned
#### Finding a problem
Look through your traces for a response that's wrong, incomplete, or off.
Click into that trace and walk the span tree. Look at what the model was given and what it did with it: did it call the right tool, pull the right data, and does the response match the context it had?
Without tracing, you'd only know the answer was wrong. With tracing, you see *exactly* where it broke: the wrong tool was called, retrieval pulled the wrong data, the model misread its context, or the prompt wasn't clear enough.