Check availability for a specific service, agent, date, and duration.
| Parameter | Type | Required | Description |
|---|---|---|---|
service_id | integer | Yes | Service ID |
agent_id | integer | Yes | Agent ID |
date | string | Yes | Date (YYYY-MM-DD) |
duration | integer | No | Service duration in minutes. If not provided, uses the service default duration. Must be a valid duration for the service. |