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

# Checkfu documentation

> Configure an Agent, start a Session, and follow its messages, tools, approvals, and results.

Checkfu runs AI agents. Choose a harness and model, or bring a harness built for your product. A harness controls how an agent uses a model and tools to complete a task. That choice affects both results and cost.

Checkfu handles execution, stores Session history, and manages access to tools and data. You can focus on what your agent does.

<CardGroup cols={2}>
  <Card title="Use an existing harness" icon="rocket" href="/getting-started/quickstart">
    Configure an Agent, start a Session, and run your first task.
  </Card>

  <Card title="Bring your own harness" icon="code" href="/guides/bring-a-custom-harness">
    Connect a harness built for your product to Checkfu.
  </Card>
</CardGroup>

## How it works

1. **Configure an [Agent](/concepts/agents).** Choose a [harness](/concepts/harnesses-and-models) and a compatible model, then set its instructions and resources.
2. **Start a [Session](/concepts/sessions-and-runs).** Select an [Environment](/concepts/work-environments) for execution. The Session records the Agent Version and Environment configuration it starts with.
3. **Send a task.** Follow progress and results through Session events. [Handle an approval](/guides/handle-an-approval) when an action requires one.

For configuration, versioning, and resource relationships, see the [product model](/concepts/product-model).

## Build your application

Give your agent [tools](/concepts/tools) to act and [context](/concepts/context) to work with. Use [Automations](/concepts/automations) to start work from schedules and events.

[Add an agent to your app](/guides/add-an-agent-to-your-app) explains how to create Sessions from your backend and show their events in your UI. The [Reference](/reference/overview) covers the HTTP API and its SDK, CLI, and MCP interfaces.


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