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

# Use built-in tools

> Add call control, runtime context, and preconfigured templates to an agent.

Built-in tools are ready to attach. You do not create, test, or publish them.
Open an agent's **Tools** page and choose **Add Tool** to find them.

| Dashboard group  | Tools                                                | Use it for                                        |
| ---------------- | ---------------------------------------------------- | ------------------------------------------------- |
| **Call control** | End call, Phone transfer, Answering machine detected | Actions that change the call                      |
| **Built-ins**    | Current date and time, User phone number             | Context the model cannot determine itself         |
| **Templates**    | Post-call summary, Create calendar event             | Preconfigured API requests for common call events |

**Webhooks** contains the blank API Request option. See
[Call an external API](/guides/agents/tools-and-mcp/api-request-tool) to configure it.

## Call control

| Tool                           | API name              | What it does                                                                  | Requirement            |
| ------------------------------ | --------------------- | ----------------------------------------------------------------------------- | ---------------------- |
| **End call**                   | `end_call`            | Speaks an optional goodbye, then ends the call                                | None                   |
| **Phone transfer**             | `transfer_call`       | Transfers the caller to another phone number                                  | An outbound connection |
| **Answering machine detected** | `voicemail_detection` | Detects an answering machine so the agent can leave a message or end the call | None                   |

**Phone transfer** places an outbound call. Configure an outbound connection
before attaching it. See
[Place calls from an agent](/guides/agents/telephony/outbound).

## Runtime context

| Tool                      | API name            | What it does                                                    | Requirement                       |
| ------------------------- | ------------------- | --------------------------------------------------------------- | --------------------------------- |
| **Current date and time** | `current_datetime`  | Returns the current date and time in a configured IANA timezone | None                              |
| **User phone number**     | `user_phone_number` | Returns the caller's phone number                               | An inbound or outbound phone call |

The model cannot reliably determine the caller's current local time. Attach
**Current date and time** when the agent offers appointments or refers to
business hours. Set `timezone` to a literal IANA timezone such as
`Europe/Madrid`.

Web sessions do not provide a phone number to **User phone number**.

## Templates

**Post-call summary** and **Create calendar event** are preconfigured API
Request tools. You provide the HTTPS endpoint. The template supplies the call
event and transcript mapping.

Templates run on a call event. See
[Run a tool on call events](/guides/agents/tools-and-mcp/run-on-call-events) for
the event contract and
[Call an external API](/guides/agents/tools-and-mcp/api-request-tool) for request
configuration.

## Configure an attachment

Select a tool from **Add Tool**, then configure its options in the attachment
editor. These values apply only to the current agent.

| Tool                       | Attachment options                       |
| -------------------------- | ---------------------------------------- |
| End call                   | `goodbye_message`, `wait_for_completion` |
| Phone transfer             | `destination`                            |
| Answering machine detected | `prompt`                                 |
| Current date and time      | `timezone`, `prompt`                     |
| User phone number          | `prompt`                                 |

Text options can include a value reference such as `{{customer_name}}`. See
[Attach a tool to an agent](/guides/agents/tools-and-mcp/attach-to-an-agent) for
argument, configuration, and pre-action message settings.

<CardGroup cols={2}>
  <Card title="Attach a tool to an agent" icon="link" href="/guides/agents/tools-and-mcp/attach-to-an-agent">
    Configure one agent's attachment and preserve its existing tools.
  </Card>

  <Card title="Create a Send SMS tool" icon="message-square" href="/guides/agents/tools-and-mcp/send-sms-tool">
    Connect Twilio and publish an organization-specific SMS tool.
  </Card>
</CardGroup>