onFunctionCall | SignalWire

Pre-execution hook called before each SWAIG function is executed. The default implementation is a no-op. Override this method in a subclass to intercept tool calls for logging, metrics, or custom dispatch logic.

This is a pre-execution hook only — it does not replace the function dispatch. The tool handler still executes regardless of what this method does. If you need to block execution, throw an error from this hook.

Parameters

name

stringRequired

Name of the SWAIG function about to execute.

args

Record<string, unknown>Required

Parsed arguments for the function, conforming to the function’s parameter schema.

rawData

Record<string, unknown>Required

The full raw SWAIG request payload, including metadata such as call_id, caller_id_number, and global_data.

Returns

void | Promise<void>

Example

1 import { AgentBase } from '@signalwire/sdk';
2 
3 class LoggingAgent extends AgentBase {
4   constructor() {
5     super({ name: 'logging-agent', route: '/logging' });
6     this.setPromptText('You are a helpful assistant.');
7     this.defineTools();
8   }
9 
10   protected override defineTools(): void {
11     this.defineTool({
12       name: 'lookup_order',
13       description: 'Look up an order',
14       parameters: {
15         type: 'object',
16         properties: { order_id: { type: 'string' } },
17         required: ['order_id'],
18       },
19       handler: async (args) => {
20         return { response: `Order ${args.order_id} is in transit.` };
21       },
22     });
23   }
24 
25   override async onFunctionCall(
26     name: string,
27     args: Record<string, unknown>,
28     rawData: Record<string, unknown>,
29   ): Promise<void> {
30     const callId = (rawData.call_id as string) ?? 'unknown';
31     console.log(`[${callId}] Tool called: ${name}(${JSON.stringify(args)})`);
32   }
33 }
34 
35 const agent = new LoggingAgent();
36 await agent.serve();