How to regulate content of json fields in Structured Outputs?

The new structured outputs feature is impressive and I’m currently evaluating it. However, I’ve observed that the generated fields cannot be controlled.

For instance, my prompt instructs to “Limit the description to a maximum of 200 words,” yet the resulting description contains approximately 400 words.

Upon further testing, I found more inconsistencies. I have a field labeled “result,” which I specified should display different numbers based on the provided content. However, the generated results are not even numbers in several tests, indicating that the prompt’s instructions are not being followed at all.

I attempted to add a description under the ‘type’ in the schema, but this resulted in an error.

At present, I am unable to find a solution to this issue or a way to control the field. Have you encountered a similar problem? If so, how did you resolve it?