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.

Return a result object from this hook to short-circuit default execution — the returned value is sent as the function response and the registered tool handler is skipped. Return void / undefined to let the normal dispatch proceed.

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

Record<string, unknown> | void | Promise<Record<string, unknown> | void> — Return a result object to short-circuit default execution; return void / undefined to proceed normally.

Example

import { AgentBase } from '@signalwire/sdk';
class LoggingAgent extends AgentBase {
  constructor() {
    super({ name: 'logging-agent', route: '/logging' });
    this.setPromptText('You are a helpful assistant.');
    this.defineTools();
  }
  protected override defineTools(): void {
    this.defineTool({
      name: 'lookup_order',
      description: 'Look up an order',
      parameters: {
        type: 'object',
        properties: { order_id: { type: 'string' } },
        required: ['order_id'],
      },
      handler: async (args) => {
        return { response: `Order ${args.order_id} is in transit.` };
      },
    });
  }
  override async onFunctionCall(
    name: string,
    args: Record<string, unknown>,
    rawData: Record<string, unknown>,
  ): Promise<void> {
    const callId = (rawData.call_id as string) ?? 'unknown';
    console.log(`[${callId}] Tool called: ${name}(${JSON.stringify(args)})`);
  }
}
const agent = new LoggingAgent();
await agent.serve();