What comes out
A complete prompt with the parts people usually leave out: delimited sections so the model knows where data ends and instructions begin, grouped constraints, and an explicit output schema naming the exact keys.
Each blueprint encodes the one decision that makes that task type reliable. For classification it is the tie-break rule; for extraction it is that an unfound field is null rather than a guess; for retrieval-grounded answering it is the refusal line and the citation requirement.
The lines that do the work
In the classification blueprint, one instruction resolves most disagreement between runs: what to do when two categories fit. Without it the model decides differently each time and you conclude it is unreliable.
In the extraction blueprint, the whole reliability rests on “a field that does not appear in the text is null”. Without it models fill gaps with plausible values, and a plausible wrong value is far more damaging than a missing one because nothing downstream flags it.
In the retrieval blueprint, two lines reduce hallucination more than any amount of retrieval tuning: decline when the passages do not cover it, and cite the passage for every claim.
Why every blueprint demands JSON
A vague output instruction is the most common cause of a parser failing in production. Naming the exact keys costs almost nothing and removes an entire class of failure — and where your provider offers a structured output mode, that enforces the shape rather than requesting it.
If you want prose, delete that section. The point is that it should be a decision rather than an omission. When output does come back wrapped in conversational text, the output validator will tell you whether the JSON underneath was fine.
After you generate
Run the result through the prompt linter once you have edited it, and price it in the system prompt analyzer if it is going to ship on every request. A paragraph that costs four figures a year and changes nothing is easier to find with a number beside it.
Save what you keep to your library — stored in this browser, no account, exportable as a file you own.