JSON body arrays in connected content API calls

Currently building out some complex connected content use cases.

Many APIs require arrays in the request, however I haven't able to make these types of requests in Braze.

I would like to make a request with this body structure:

{
  "model": "sonar-pro",
  "messages": [
    {
      "role": "system",
      "content": "Be precise and concise."
    },
    {
      "role": "user",
      "content": "How many stars are there in our galaxy?"
    }
  ],
  "max_tokens": 123,
  "temperature": 0.2
}

For context, this is a request to Perplexity API.

So far, in testing through webhook.site I haven't been able to properly make this request. I have gotten close using some complex url-encoding but its not 100%. 

Is there any known limitation of using arrays within the body of requests or a solution/workaround to this issue?

Cheers!