> ## Documentation Index
> Fetch the complete documentation index at: https://wb-21fd5541-codex-link-agent-evals-docs.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# W&B Weave

> Track, test, and improve language model apps with W&B Weave

W\&B Weave is an observability and evaluation platform that helps you track, evaluate, and improve your agents and LLM applications. With Weave, you can:

* [Trace and collect metrics about your agents](/weave/agent-integration-quickstart) built with popular SDKs and harnesses using Weave OTel-compatible SDK
* [Manually instrument your application's LLM calls and arbitrary functions](/weave/quickstart) to trace, version, and collect feedback about your application
* [Evaluate](/weave/tutorial-eval) your agent's or application's responses using LLM judges and custom scorers

## Get started

Select your workload type and then use the following docs to guide you through the basics of how to use Weave's suite of tools. For more information about the difference between workloads, see [What is Weave?](/weave/concepts/what-is-weave)

<Tabs>
  <Tab title="Trace an agent">
    <CardGroup cols={3}>
      <Card title="Integrate Weave with an agent" icon="plug" href="/weave/agent-integration-quickstart">
        Pick a built-in integration for your agent SDK or harness and start tracing sessions, turns, LLM calls, and tool calls in the Agents view.
      </Card>

      <Card title="Set up custom agent observability" icon="code" href="/weave/custom-agents-quickstart">
        Trace a custom multi-turn agent with the Weave SDK to capture sessions, LLM calls, and tool calls as OpenTelemetry spans.
      </Card>

      <Card title="View agent metrics in Weave UI" icon="chart-line" href="/weave/guides/tracking/view-agent-activity">
        Trace a basic call to an LLM and review the inputs, outputs, and code in your W\&B account.
      </Card>
    </CardGroup>
  </Tab>

  <Tab title="Trace functions with Ops and Calls">
    <CardGroup cols={3}>
      <Card title="Quickstart: Instrument and trace functions" icon="chart-line" href="/weave/quickstart">
        Start by tracing a basic call to an LLM and reviewing the data in your W\&B account.
      </Card>

      <Card title="Get started evaluating your app" icon="clipboard-check" href="/weave/tutorial-eval">
        Learn how to build an evaluation pipeline using Weave scorers to test and track your application's performance.
      </Card>

      <Card title="Evaluate a RAG application" icon="search" href="/weave/tutorial-rag">
        Build and evaluate RAG applications using Weave with LLM judges to measure retrieval quality.
      </Card>
    </CardGroup>
  </Tab>
</Tabs>

## Install Weave

W\&B Weave provides Python and TypeScript libraries. To install the Weave library, run the following command:

<Tabs>
  <Tab title="Python">
    ```bash theme={null}
    pip install weave
    ```
  </Tab>

  <Tab title="TypeScript">
    ```bash theme={null}
    npm install weave
    ```
  </Tab>
</Tabs>

To start using the Weave library, create a [Weights & Biases (W\&B) account](https://wandb.ai) and an [API key at User Settings](https://wandb.ai/settings). The API key allows you to authenticate to your W\&B account and start sending data to it.