const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    model: 'openai/gpt-5-nano',
    stream: false,
    messages: [{role: 'user', content: 'What is the current datetime in Europe/London?'}],
    tools: [{type: 'gateway:datetime', parameters: {timezone: 'Europe/London'}}],
    tool_choice: 'auto'
  })
};

fetch('https://api.phaseo.app/v1/chat/completions', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

{
  "id": "<string>",
  "object": "<string>",
  "created": 123,
  "model": "<string>",
  "choices": [
    {
      "index": 123,
      "message": {
        "role": "system",
        "content": "<string>",
        "name": "<string>",
        "tool_calls": [
          {
            "id": "<string>",
            "type": "function",
            "function": {
              "name": "<string>",
              "arguments": "<string>",
              "description": "<string>",
              "parameters": {}
            }
          }
        ],
        "images": [
          {
            "type": "image_url",
            "image_url": {
              "url": "<string>"
            },
            "mime_type": "<string>"
          }
        ],
        "audios": [
          {
            "type": "audio_url",
            "audio_url": {
              "url": "<string>"
            },
            "mime_type": "<string>",
            "format": "wav"
          }
        ],
        "tool_call_id": "<string>"
      },
      "finish_reason": "stop"
    }
  ],
  "usage": {
    "prompt_tokens": 123,
    "completion_tokens": 123,
    "total_tokens": 123,
    "server_tool_use": {
      "datetime_requests": 1
    }
  }
}