Hey guys, facing an issue with vapi tool call results. In the Call Logs in Vapi, it says my tool isn't returning anything, and the assistant says they're not getting any available time slots (the tool checks available time slots):

{
  "role": "tool_calls",
  "time": 1734733756187,
  "message": "",
  "toolCalls": [
    {
      "id": "call_K4u2CIHgZQI38mPDIOvpPWJn",
      "type": "function",
      "function": {
        "name": "check_date_availability",
        "arguments": "{\"preferred_date\": \"tomorrow 2pm\"}"
      }
    }
  ],
  "secondsFromStart": 15.84
}

{
  "name": "check_date_availability",
  "role": "tool_call_result",
  "time": 1734733757622,
  "result": "No result returned.",
  "toolCallId": "call_K4u2CIHgZQI38mPDIOvpPWJn",
  "secondsFromStart": 17.275
}

However, in the Webhook Logs in Vapi, in the request where I make the tool call, I can clearly see that my response is in the right format:

{
  "results": [
    {
      "toolCallId": "call_K4u2CIHgZQI38mPDIOvpPWJn",
      "result": [
        "08:00:00",
        "08:30:00"
      ]
    }
  ]
}

Anyone have any idea what the problem could be?