Structured Output Schema Builder
Generate OpenAI, Anthropic, MCP, or plain JSON Schema wrappers from sample output
Outputs the `text.format` JSON Schema object for OpenAI Structured Outputs, with `strict: true` and object schemas locked down.
Sample JSON
Generated Output
The schema is generated entirely in your browser from the sample you paste here. No provider APIs or server-side processing are involved.
Generate provider-ready schemas for OpenAI, Anthropic, and MCP
Modern LLM APIs accept JSON Schema, but each provider expects a slightly different wrapper — OpenAI Structured Outputs require strict mode and additionalProperties: false, Anthropic tools want input_schema, MCP servers want inputSchema. This builder turns one sample JSON into the right wrapper for each, so you don't hand-edit YAML across three SDKs.
Use the builder when you need to
Lock down an OpenAI Structured Output
Generate a strict schema with additionalProperties: false so the model can't return unexpected keys.
Build a Claude tool definition
Wrap your schema as input_schema with name and description, ready to paste into the tools array.
Validate an MCP tool's inputSchema
Produce inputSchema-compatible output for MCP servers that expect a specific tool definition shape.
How to build a structured output schema
- 1
Paste a sample of the structured JSON you want the model to return.
- 2
Pick a preset: plain JSON Schema, OpenAI, Anthropic, or MCP.
- 3
Copy the generated schema and paste it into your provider request.
Keep going
Generate plain JSON Schema
Use this when the consumer is your own validation library, not a model provider.
Validate model output
Confirm the model actually returned what the schema requires.
Anthropic-specific builder
Use the focused builder when you only need Claude tool definitions.
Repair and validate model JSON
Combine repair and schema checks for end-to-end model output validation.
Common structured-output workflows
Generate a schema that satisfies Structured Outputs requirements without writing it by hand.
Lift the JSON shape, regenerate the wrapper, and paste it into the new provider's request.
Use one canonical sample to generate consistent schemas for every provider you target.
関連ツール
よくある質問
It turns a sample JSON document into either a plain JSON Schema or a provider-ready wrapper for OpenAI Structured Outputs, Anthropic tool input_schema, or MCP inputSchema definitions.
No. The builder runs entirely in your browser. It never calls OpenAI, Anthropic, or any other API.
OpenAI Structured Outputs require object schemas to explicitly disallow undeclared keys when you want strict schema enforcement. The builder applies that automatically in the OpenAI preset.
Yes. The generated output is just JSON. Copy it into your codebase or another editor and tighten enums, descriptions, optional fields, or nested constraints as needed.