Querying agent utilization metrics (tHandle, tAcw, tHold) by 30-minute intervals via Analytics API

Trying to pull granular agent utilization data using the /api/v2/analytics/agents/summary endpoint. I need tHandle, tAcw, and tHold broken down into 30-minute buckets.

Current query:

{
 "dateFrom": "2023-10-01T00:00:00.000Z",
 "dateTo": "2023-10-01T23:59:59.999Z",
 "interval": "PT30M",
 "metrics": ["tHandle", "tAcw", "tHold"],
 "groupBy": ["agentId"]
}

The response aggregates the day instead of returning 48 intervals. Does the summary API support this granularity, or do I need to hit the events endpoint and aggregate manually?