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

# Tool calls

> Let your agent take actions and fetch data during a call.

Tools let your agent do more than talk — transfer a call, look up information, check availability, or book an appointment while the conversation is happening.

## Built-in tools

| Tool                    | What it does                                                                       |
| ----------------------- | ---------------------------------------------------------------------------------- |
| `transferCall`          | Transfers the call to another number.                                              |
| `transferCallSecondary` | Transfers the call to a secondary destination.                                     |
| `sipColdTransfer`       | Transfers the call over SIP without staying on the line.                           |
| `sipWarmTransfer`       | Transfers the call over SIP while briefly staying on the line to hand off context. |
| `pauseTimer`            | Pauses call timing logic, for example while waiting on hold.                       |
| `queryKB`               | Searches a knowledge base for information to answer the caller.                    |
| `numberValidation`      | Validates a phone number the caller provides.                                      |

## Custom API tools

The `apiRequest` tool lets your agent call any external API during the call — for example, to look up an order or submit a form.

<Steps>
  <Step title="Open the Tools section">
    In your agent, open the **Tools** section and add a new custom API tool.
  </Step>

  <Step title="Name it">
    Give the tool a name the agent will use to decide when to call it.
  </Step>

  <Step title="Configure the request">
    Set the HTTP method and URL, and a request template for the body or query parameters.
  </Step>

  <Step title="Add authentication and headers">
    Configure any headers or authentication the API requires.
  </Step>

  <Step title="Set the response path">
    Specify where in the API's response the value the agent needs lives, so the agent can use it in the conversation.
  </Step>
</Steps>

## Calendar and booking tools

<AccordionGroup>
  <Accordion title="Lead Connector">
    Check availability and create appointments through Lead Connector, with support for rescheduling.
  </Accordion>

  <Accordion title="Google Calendar">
    Check availability and create appointments on a connected Google Calendar, with support for rescheduling.
  </Accordion>

  <Accordion title="Cal.com">
    Check availability and create appointments through Cal.com, with support for rescheduling.
  </Accordion>

  <Accordion title="Calendly">
    Check availability and create appointments through Calendly, with support for rescheduling.
  </Accordion>
</AccordionGroup>

## Enable and configure tools

Each agent has its own set of enabled tools. Open the **Tools** section, enable the tools your agent needs, and fill in any tool-specific configuration.

## Review tool call logs

After a call, you can review which tools the agent called and what they returned from the call's detail view. See [Call logs](/monitoring/call-logs) for more.

## Next step

[Call outcomes](/build-voice-agents/call-outcomes) to classify how each call ended.