What is a JSON schema?
A JSON schema is a written contract for structured data: which fields exist, which are required, and what type they are. Structured output asks for a shape. A schema is the strict version of that shape that software can reject.
Also called: schema
In plain English
You want finish, width, and room, or an error. A schema lets the workflow refuse a blob that skipped finish. You do not need to become a programmer to insist on the fields. You do need to list them. JSON mode without a schema only promises 'this is data-shaped,' not 'these are the right fields.' The schema is the shape you promised the next step. Name, town, stairs, or empty. If you do not check the shape, the model will sometimes give you a paragraph anyway and the job card will choke. Validate before you write to the sheet. A schema is overhead when a person is the next reader. It is the job when software is the next reader. Add a field only when a downstream step reads it. Decorative fields become required by accident and then every run looks broken.
How an owner would use it
Use a schema when the next step is a machine: a sheet, a CRM, an order form. Skip it when a person is reading a short email. Test a missing field and confirm the run stops.
Common mistakes
A schema that marks everything optional will accept an empty object. A schema you copied from a tutorial will not match your form. Do not show raw JSON to a customer. Map the fields into words after they pass the check. Do not treat a schema as a security boundary. It checks shape, not permission.
A worked example
A cabinet shop
No finish, no work order
This is an illustration, not a customer result. The intake note must yield width, species, and finish. If finish is absent, the schema check fails and the job stays in the exception list. The drafter does not write 'natural' because most kitchens are natural.
Related terms
Prompts and guides
Questions owners ask
What is a JSON schema?
It is a formal list of fields and types so software can accept or reject a structured AI answer.
How do I use a schema without living in code?
List the required fields in the automation tool's structured-output or form step, and fail the run when one is missing.
Does a schema stop hallucinations?
It can force a blank to be explicit. It cannot make a present value true. You still compare important fields to the source note.
Product guides are on AI apps for business.