> ## Documentation Index > Fetch the complete documentation index at: https://openrouter.ai/docs/llms.txt > Use this file to discover all available pages before exploring further. # MessagesOutputConfigFormat A schema to specify Claude's output format in responses. See [structured outputs](https://platform.claude.com/docs/en/build-with-claude/structured-outputs). ## Example Usage ```typescript theme={null} import { MessagesOutputConfigFormat } from "@openrouter/sdk/models"; let value: MessagesOutputConfigFormat = { schema: {}, type: "json_schema", }; ``` ## Fields | Field | Type | Required | Description | | -------- | --------------------------------------------------------------------------------------------- | -------------------- | ----------- | | `schema` | Record\ | :heavy\_check\_mark: | N/A | | `type` | [models.MessagesOutputConfigTypeJSONSchema](../models/messagesoutputconfigtypejsonschema.mdx) | :heavy\_check\_mark: | N/A |