> ## Documentation Index
> Fetch the complete documentation index at: https://docs.idun-group.com/llms.txt
> Use this file to discover all available pages before exploring further.

# LangSmith

> Set up LangSmith observability to debug, test, evaluate, and monitor your agents.

Set up LangSmith to debug, trace, and monitor your agents from the LangSmith dashboard.

<Tip>
  Before starting, complete the [quickstart guide](/quickstart) to have an agent running on Idun Engine.
</Tip>

## Set up LangSmith observability

<Steps>
  <Step title="Get your LangSmith API key">
    If you do not have a LangSmith API key yet:

    1. Go to [LangSmith](https://smith.langchain.com/)
    2. Sign up or log in to your account
    3. Navigate to **Settings** (gear icon) > **API Keys**
    4. Click **Create API Key**
    5. Copy your **API Key**
  </Step>

  <Step title="Configure LangSmith in the standalone">
    Open the running standalone at `/admin/observability/` and click **LangSmith**. Fill in:

    * **API Key**: Your LangSmith API key (starts with `lsv2-...`)
    * **Project Name**: The name of the project in LangSmith (for example, `default` or `prod-agent`)
    * **Endpoint**: (Optional) Custom endpoint if you are self-hosting LangSmith (defaults to `https://api.smith.langchain.com`)
    * **Run Name**: (Optional) Display name for each trace run in LangSmith (for example, `my-agent`)

    <Frame>
      <img src="https://mintcdn.com/idunlabs/SjVPzIbyPaldjUKK/images/ui/admin-observability-langsmith.png?fit=max&auto=format&n=SjVPzIbyPaldjUKK&q=85&s=7ba680b856b71c221f09f1b048d535ca" alt="Observability admin page with LangSmith selected" width="1911" height="1040" data-path="images/ui/admin-observability-langsmith.png" />
    </Frame>

    Save the form. The reload pipeline re-instantiates the engine with the new observability config; the next agent run starts streaming spans to LangSmith.

    <Warning>
      Keep your API key secure. Do not commit it to version control or share it publicly.
    </Warning>
  </Step>
</Steps>

Alternatively, configure LangSmith in your `config.yaml` for first-boot seeding or engine-only mode:

```yaml config.yaml theme={"theme":{"light":"github-light","dark":"github-dark"}}
observability:
  - provider: "LANGSMITH"
    enabled: true
    config:
      api_key: "${LANGSMITH_API_KEY}"
      project_name: "prod-agent"
      run_name: "my-agent"
```

## View observability data

Once your agent is running with observability enabled:

1. Interact with your agent through the chat UI at `/` or the API at `/agent/run`
2. Open your LangSmith dashboard at [smith.langchain.com](https://smith.langchain.com/)
3. Navigate to your project to view traces

You will see traces showing the execution run tree, LLM inputs/outputs, and latency. Each trace run is named after your agent by default.

## Best practices

* Use distinct projects for development and production environments
* Tag runs to filter traces when investigating specific issues (configured within agent logic)
* Review error traces in LangSmith to identify and resolve problems quickly

## Troubleshooting

<AccordionGroup>
  <Accordion title="Observability not working?">
    1. **Check API key**: Verify it is valid and has the required permissions
    2. **Verify project name**: Traces are sent to the "default" project if the project name is not specified or is incorrect
    3. **Check tracing toggle**: Confirm the tracing toggle is enabled in the configuration
  </Accordion>
</AccordionGroup>

## Next steps

<Card title="Local trace store" icon="database" horizontal href="/observability/traces">
  Inspect every agent run in the bundled admin UI alongside LangSmith.
</Card>

<Card title="Observability overview" icon="chart-line" horizontal href="/observability/overview">
  Compare built-in providers and their configuration shapes.
</Card>

<Card title="Custom handler" icon="puzzle" horizontal href="/observability/custom-handler">
  Write a handler for any provider not on the shipping list.
</Card>