# Tool call

NavTalk supports integration of digital humans with external systems through function calling, enabling functionalities such as weather inquiries, knowledge base retrieval, and business system triggers.

## Step 1: Define Function Tools

When establishing a WebSocket session, configure the tools in the `session.update` request body:

```javascript
tools: [
  {
    "type": "function",
    "name": "function_call_judge",
    "description": "Automatically triggers function extension calls when user requests exceed the current conversation capabilities.",
    "parameters": {
      "type": "object",
      "properties": {
        "userInput": {
          "type": "string",
          "description": "Raw user request content to be processed"
        }
      },
      "required": ["userInput"]
    }
  }
]

```

## Step 2: Receive Callback Events

When the function is triggered, the WebSocket will receive messages of the following type:

```javascript
if (data.type === "response.function_call_arguments.done") {
  handleFunctionCall(data);
}
```

| field       | meaning                                                      |
| ----------- | ------------------------------------------------------------ |
| `type`      | Fixed as `response.function_call_arguments.done`             |
| `arguments` | The parameters for the function call (in JSON string format) |
| `call_id`   | The current unique identifier for the function call          |

## Step 3: Handle Function Calls

```javascript
function handleFunctionCall(eventJson) {
  try {
    const functionCallArgs = JSON.parse(eventJson.arguments);
    const userInput = functionCallArgs.userInput;
    const callId = eventJson.call_id;

    handleWithMemAgent(userInput)
      .then(result => {
        sendFunctionCallResult(result, callId);
      })
      .catch(error => {
        console.error("Function call failed: ", error);
      });

  } catch (error) {
    console.error("Parameter parsing failed: ", error);
  }
}

```

## Step 4: Call Backend Interfaces to Handle Business Logic

You can pass the `userInput` to the business system or middleware interface, such as a weather API or CRM system:

```javascript
function handleWithMemAgent(userInput) {
  return new Promise(async (resolve, reject) => {
    const chatId = await getFromChromeStorage("chatId");

    fetch(`${baseUrl}/api/realtime_function_call`, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({
        userInput,
        license,
        chatId
      }),
    })
    .then(response => response.text())
    .then(result => resolve(result))
    .catch(error => reject(error));
  });
}
```

## Step 5: Return Results to AI Conversation

After processing the results, they need to be pushed back to the WebSocket, prompting the AI to continue responding:

```javascript
function sendFunctionCallResult(result, callId) {
  const resultJson = {
    "type": "conversation.item.create",
    "item": {
      "type": "function_call_output",
      "output": result,
      "call_id": callId
    }
  };

  socket.send(JSON.stringify(resultJson));

  // Actively trigger AI response
  socket.send(JSON.stringify({ "type": "response.create" }));
}

```

## Common Application Scenario Examples

| scene                    | user input                                           | system action                                            |
| ------------------------ | ---------------------------------------------------- | -------------------------------------------------------- |
| Check the weather        | "What will the weather be like in Beijing tomorrow?" | Call the weather API and return the weather forecast     |
| Query the knowledge base | "How to integrate Function Calling with NavTalk?"    | Access the internal knowledge system to retrieve answers |
| Control devices          | "Turn on the conference room lights."                | Call the IoT interface to control hardware devices       |