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429You can denote optional fields by adding `null` as a `type` option (see example below).429You can denote optional fields by adding `null` as a `type` option (see example below).
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431If you send `strict: true` and your schema does not meet the requirements above,
432the request will be rejected with details about the missing constraints. If you
433omit `strict`, the default depends on the API: Responses requests will
434normalize your schema into strict mode (for example, by setting
435`additionalProperties: false` and marking all fields as required), which can
436make previously optional fields mandatory, while Chat Completions requests
437remain non-strict by default. To opt out of strict mode in Responses and keep
438non-strict, best-effort function calling, explicitly set `strict: false`.
439
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