Nice to have an endpoint which takes care of this. I've been doing this manually, it's a fairly simple process:

* Add "Output your response in json format, with the fields 'x', which indicates 'x_explanation', 'z', which indicates 'z_explanation' (...)" etc. GPT-4 does this fairly reliably.

* Validate the response, repeat if malformed.

* Bam, you've got a json.

I wonder if they've implemented this endpoint with validation and carefully crafted prompts on the base model, or if this is specifically fine-tuned.