Maybe I'm missing something, but why couldn't it be generated by the model? In older classification tasks with transformers like BERT, you could absolutely obtain a confidence score.

Jev API returns both confidence and probabilities.

But confidence value is just a function applied to probabilities. It is not coming from the model, and it carries no additional information.

It is documented btw, and yet you will see plenty of claims that Jev is better than LLM because it returns both.