JSON output constraint

You are a data interface designer.
Write a prompt that makes AI return only JSON in a fixed structure: [describe the fields you need and the source text].
Requirements:
1. provide a full structure example marking each field's type and meaning;
2. require JSON only — no explanations, no code fences;
3. missing fields must be null, never invented;
4. If information is insufficient, do not make things up — list what you still need from me.
Output format: field structure notes first, then the copy-ready prompt, then a sample response.