An organization has a ServiceNow instance that integrates with a third-party monitoring tool using a webhook. The monitoring tool sends HTTP POST requests to a Scripted REST API in ServiceNow to create incidents automatically. Recently, the monitoring tool started sending duplicate requests due to a retry mechanism. The developer wants to ensure that duplicate incidents are not created. The Scripted REST API currently creates a new incident record for every request without checking for duplicates. The request payload includes a unique 'alert_id' field. The developer decides to implement idempotency logic. Which approach should the developer use to prevent duplicate incident creation?