ResponseFormat

Defined in: packages/ai/src/types.ts:1115

Structured output format specification.

Constrains the model's output to match a specific JSON structure. Useful for extracting structured data, form filling, or ensuring consistent response formats.

See

• https://platform.openai.com/docs/guides/structured-outputs
• https://sdk.vercel.ai/docs/ai-sdk-core/structured-outputs

Type Parameters

TData

TData = any

TypeScript type of the expected data structure (for type safety)

Properties

__data?

optional __data?: TData;

Defined in: packages/ai/src/types.ts:1193

Internal

Type-only property to carry the inferred data type.

This is never set at runtime - it only exists for TypeScript type inference. Allows the SDK to know what type to expect when parsing the response.

json_schema?

optional json_schema?: object;

Defined in: packages/ai/src/types.ts:1132

JSON schema specification (required when type is "json_schema").

Defines the exact structure the model's output must conform to. OpenAI's structured outputs will guarantee the output matches this schema.

description?

optional description?: string;

Optional description of what the schema represents.

Helps document the purpose of this structured output.

Example

"User profile information including name, email, and preferences"

name

name: string;

Unique name for the schema.

Used to identify the schema in logs and debugging. Should be descriptive (e.g., "user_profile", "search_results").

schema

schema: Record<string, any>;

JSON Schema definition for the expected output structure.

Must be a valid JSON Schema (draft 2020-12 or compatible). The model's output will be validated against this schema.

See

https://json-schema.org/

Example

{
     *   type: "object",
     *   properties: {
     *     name: { type: "string" },
     *     age: { type: "number" },
     *     email: { type: "string", format: "email" }
     *   },
     *   required: ["name", "email"],
     *   additionalProperties: false
     * }

strict?

optional strict?: boolean;

Whether to enforce strict schema validation.

When true (recommended), the model guarantees output will match the schema exactly. When false, the model will "best effort" match the schema.

Default: true (for providers that support it)

See

https://platform.openai.com/docs/guides/structured-outputs#strict-mode

type

type: "json_object" | "json_schema";

Defined in: packages/ai/src/types.ts:1124

Type of structured output.

• "json_object": Forces the model to output valid JSON (any structure)
• "json_schema": Validates output against a provided JSON Schema (strict structure)

See

https://platform.openai.com/docs/api-reference/chat/create#chat-create-response_format