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

# Steps

> A step is a single LLM call or sub-operation within a trace.

A step records one unit of work inside a [trace](/concepts/traces): usually an LLM call, a tool call, or a stage of your pipeline. You create a step by wrapping the work in `ctx.TrackStepAsync` with a name and an input.

## How steps fit in

Steps belong to a trace. The step name is how Veval matches steps across runs:

* [Replay](/concepts/replay) serves recorded outputs by step name.
* [Assertions](/concepts/assertions) like `StepExists` and `ToolCalled` look steps up by name.
* [Snapshots](/concepts/snapshots) align steps by name and position to find what changed.

Give each step a stable name that describes what it does, like `classify` or `answer`.

## What a step records

| Field | Description |
| - | - |
| Name | The name you pass to `TrackStepAsync`. |
| Input | The input you pass to `TrackStepAsync`. |
| Output | The value the step returned. |
| Status | Whether the step completed or failed with an error. |
| Duration | How long the step took. |
| Model, tokens, cost | Set with `handle.SetMeta` using the `model`, `tokens_in`, `tokens_out`, and `cost_usd` keys. |
| Type | Set with `handle.SetMeta("type", "tool")` to mark a tool call. |
| Metadata | Any other key you set with `handle.SetMeta`. |

See [StepHandle metadata keys](/guides/tracing#stephandle-metadata-keys) for the full list.

## Deep dives

<CardGroup cols={2}>
  <Card title="Instrument your agent" icon="wave-pulse" href="/guides/tracing">
    Record steps and attach metadata.
  </Card>

  <Card title="Traces" icon="route" href="/concepts/traces">
    The run that steps belong to.
  </Card>
</CardGroup>