Add a custom tool

export default function customerTools(pi) {
  pi.registerTool({
    name: 'lookup_customer',
    label: 'Look up customer',
    description: 'Look up a customer using their stable customer ID.',
    parameters: {
      type: 'object',
      properties: {
        customerId: {
          type: 'string',
          description: 'Stable customer identifier.',
        },
      },
      required: ['customerId'],
      additionalProperties: false,
    },
    async execute(_toolCallId, { customerId }, _signal, _onUpdate, ctx) {
      const source = ctx.external?.provider ?? 'api';

      return {
        content: [
          {
            type: 'text',
            text: `Customer ${customerId} requested from ${source}.`,
          },
        ],
        details: {
          customerId,
          source,
        },
      };
    },
  });
}

async execute(toolCallId, params, signal, onUpdate, ctx) {
  // ...
}

return {
  content: [{ type: "text", text: "Result visible to the model" }],
  details: { optional: "structured diagnostic data" },
};

throw new Error('Customer record was not found.');