LLM Structured Output Builder
Build or import a final-response JSON Schema and check a reviewed OpenAI, Anthropic and Gemini compatibility subset locally.
Shape the model’s final answer, not a function’s arguments. Build up to 40 fields at four levels, or import 32 KiB JSON for a conservative compatibility review.
Response schema
Compatibility and output
Compatibility is checked against a reviewed subset, not every JSON Schema keyword or provider model. Unknown constructs are never silently discarded. Refusal, truncation and provider behavior still require validation of actual responses.
Rules verified 2026-10-13. OpenAI schema rules Anthropic schema rules Gemini schema rules
Build or import a schema, then validate compatibility.
Final answers have a schema.
Structured output defines the model’s final response. Function calling instead describes arguments for an application tool. This workspace generates response configuration; it does not call a model or validate a live model answer.
Compatibility without silent rewrites.
OpenAI strict responses require an object root, closed objects and all properties required. Anthropic permits optional properties but requires closed objects and does not accept numeric bounds. Gemini’s reviewed subset supports numeric bounds. Unknown keywords, references and composition are reported as unverified, never silently removed.
Import without reconstruction.
Paste an existing schema to inspect compatibility; it does not need to fit the visual builder. Generic output preserves the imported schema. Provider output is withheld when findings remain. Nullable means a value may be null; optional means a property may be absent. The tool does not interchange these meanings.
Conservative and local.
Imports allow 32 KiB UTF-8, 24 JSON container levels, eight schema levels and 200 nodes. The visual builder allows 40 fields/item schemas and four levels. Duplicate keys and inexact numeric conversion are rejected. No schema code or regular expressions are executed, and no references are fetched. Local compatibility does not guarantee provider acceptance or a complete response; handle refusal, truncation and Claude’s documented enum capitalization caveat in your application.