Most people make the mistake of not including the time in your prompt. Include that. I don't see one in yours. { "name": "get_free_slots", "role": "tool_call_result", "time": 1752515959852, "result": "[\n {\n \"type\": \"text\",\n \"text\": \"{\\\"2025-07-14\\\":{\\\"slots\\\":[\\\"2025-07-14T14:00:00-04:00\\\",\\\"2025-07-14T14:30:00-04:00\\\",\\\"2025-07-14T15:00:00-04:00\\\",\\\"2025-07-14T15:30:00-04:00\\\",\\\"2025-07-14T16:00:00-04:00\\\",\\\"2025-07-14T16:30:00-04:00\\\",\\\"2025-07-14T17:00:00-04:00\\\",\\\"2025-07-14T17:30:00-04:00\\\",\\\"2025-07-14T18:00:00-04:00\\\",\\\"2025-07-14T18:30:00-04:00\\\"]},\\\"2025-07-15\\\":{\\\"slots\\\":[\\\"2025-07-15T10:00:00-04:00\\\",\\\"2025-07-15T10:30:00-04:00\\\",\\\"2025-07-15T11:00:00-04:00\\\",\\\"2025-07-15T11:30:00-04:00\\\",\\\"2025-07-15T12:00:00-04:00\\\",\\\"2025-07-15T12:30:00-04:00\\\",\\\"2025-07-15T13:00:00-04:00\\\",\\\"2025-07-15T13:30:00-04:00\\\",\\\"2025-07-15T14:00:00-04:00\\\",\\\"2025-07-15T14:30:00-04:00\\\",\\\"2025-07-15T15:00:00-04:00\\\",\\\"2025-07-15T15:30:00-04:00\\\",\\\"2025-07-15T16:00:00-04:00\\\",\\\"2025-07-15T16:30:00-04:00\\\",\\\"2025-07-15T17:00:00-04:00\\\",\\\"2025-07-15T17:30:00-04:00\\\",\\\"2025-07-15T18:00:00-04:00\\\",\\\"2025-07-15T18:30:00-04:00\\\"]},\\\"traceId\\\":\\\"6b557714-752a-4fa6-a59f-aa5067ff7507\\\"}\"\n }\n]", "toolCallId": "call_KxeIcaeHFm2orSIdLjG7b5hI", "secondsFromStart": 39.877 } I actually don't use the integration inside of VAPI, but this is what the request looks like.