Is any call that returns the current assignee of the Task?
You can use the GET endpoint to query a task and its related fields.
You can also customize the data that is returned by the GET /tasks/{task_gid} endpoint using the opt_fields query parameter. For example:
GET /tasks/12345678/?opt_fields=assignee,assignee.name,assignee.email
will return only assignee data for the task, and include the assignee’s email address, which is something you don’t get by default. Hope this helps!