Structured Output Prompting: Get JSON, Not Prose

Structured output means asking the model to return data in a fixed shape—JSON, a table, or a labeled list—instead of free paragraphs. Start your prompt by pasting the exact schema you expect, key by key, and add a one-line description after each field. Ambiguity is the enemy: 'return a list' invites variety, while 'return {"title":string,"tags":string[3]}' locks it down.

Add three guardrails that catch most failures. First, state 'return only valid JSON, no markdown, no code fences' so nothing wraps your payload. Second, give a filled-in example alongside the empty schema—models copy patterns faster than they parse rules. Third, constrain lengths and enums explicitly ('status must be one of: draft, live, archived') so downstream code never hits a surprise value.

On CinderHub, this pays off when you chain steps: a storyboard prompt that returns scene objects with fixed keys feeds straight into the image and video stages with no reformatting. Always validate the result by parsing it in code, not by eye—if parsing fails, feed the error back to the model and ask it to fix only the JSON. Treat the schema as a contract, and every model in your pipeline can honor it.