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

# Custom Function Calling

> Integrate external APIs and workflows into your AI agents with function calling.

## What is Function Calling?

Function calling enables your AI agents to execute real-time actions during conversations by calling external APIs and triggering workflows.

***

## Capabilities

<CardGroup cols={2}>
  <Card title="API Integration" icon="plug" href="/guides/custom-functions/api-integration">
    Connect to external APIs and services
  </Card>

  <Card title="Function Examples" icon="code" href="/guides/custom-functions/examples">
    Ready-to-use function examples for common use cases
  </Card>

  <Card title="Best Practices" icon="star" href="/guides/custom-functions/best-practices">
    Tips for reliable and secure function calling
  </Card>

  <Card title="Testing Functions" icon="vial" href="/guides/custom-functions/testing">
    How to test and debug custom functions
  </Card>
</CardGroup>

***

## How It Works

<Steps>
  <Step title="AI Reads Function">
    The AI understands what the function does from its description
  </Step>

  <Step title="Detects Trigger">
    Based on conversation, AI decides when to call the function
  </Step>

  <Step title="Extracts Parameters">
    AI collects required parameters from the conversation
  </Step>

  <Step title="Executes API Call">
    Dialgen makes the HTTP request to your endpoint
  </Step>

  <Step title="Returns Response">
    API response feeds back to AI for natural continuation
  </Step>
</Steps>

***

## Quick Example

```json theme={null}
{
  "name": "check_order_status",
  "description": "Checks the customer's order status. Call this when the customer asks about their order, delivery, or tracking.",
  "parameters": {
    "type": "object",
    "properties": {
      "order_id": {
        "type": "string",
        "description": "The order number"
      }
    },
    "required": ["order_id"]
  },
  "api_endpoint": "https://api.yourcompany.com/orders/status",
  "http_method": "POST"
}
```

<Tip>
  The description is critical. The AI relies on it to know when to trigger the function.
</Tip>

***

## Use Cases

### CRM Integration

Update customer records, add notes, change lead status.

### Appointment Booking

Check availability and book appointments in real-time.

### Order Management

Check order status, process returns, track shipments.

### Payment Processing

Process payments, check balances, send invoices.

### Data Retrieval

Fetch customer data, account information, product details.

***

## Next Steps

<CardGroup cols={2}>
  <Card title="API Integration" icon="plug" href="/guides/custom-functions/api-integration">
    Learn how to integrate external APIs
  </Card>

  <Card title="Examples" icon="code" href="/guides/custom-functions/examples">
    View ready-to-use function examples
  </Card>
</CardGroup>