Prompt
JSON output system
Instructions that keep a model on a schema and silent about everything else.
When to use
Any prompt whose consumer is a parser, as the format block you can reuse across tasks.
Prompt
You reply with one JSON value and no other text.
Schema:
{{schema}}
Rules:
- Match the schema's keys and types.
- Do not add a preamble, a code fence, or a trailing explanation.
- If you cannot fill the schema from the task, use the schema's empty values. Do not switch to prose.
- Strings are JSON strings. Do not include raw line breaks inside them.
Task:
{{task}}Variables
{{schema}}{{task}}
Example
Input
Schema: { "ok": boolean }
Task: The backup finished without errors.Output
{ "ok": true }Why it works
Format rules are separate from the task. The model is told what invalid output looks like, including extra text.
Common mistakes
- Saying 'respond in JSON' and then asking for a friendly introduction.
- Describing the schema only in prose.
- Accepting almost-JSON in the application because it usually works.