Architecture

Structured Outputs

Forcing the AI to answer in an exact data format, like filling in a form, so programs can read it reliably.

Definition

An API feature that constrains a model's response to a supplied JSON schema through constrained decoding, so output always parses and has the required fields and types. On Claude, JSON outputs use output_config.format with type json_schema, and strict tool use (strict: true) applies the same guarantee to tool inputs. Responses that stop for a refusal or max_tokens may not match the schema; the older output_format parameter is deprecated.

Example

With a schema requiring name (string) and severity (enum), every reply parses with JSON.parse and never misses a field.