How the schema reached the model: forced_tool, a forced schema tool call the gateway lifted; provider_schema, a
hop whose payload carried the schema (OpenAI's strict json_schema, Gemini's responseSchema, Anthropic's JSON output
format, whose text answer the gateway lifts, and a forced tool call that did not parse or that the output limit
stopped); prompt_only, the schema reached the model in the prompt alone (a record schema on a Claude model that
refuses a forced choice, say).
Where the last check ran: on the model's reply, or on the text an output guardrail rewrote.
Optional issues
Model calls the turn made for the structured reply.