What does strict mode change?

It removes $schema, $id and title, sets additionalProperties: false on every object, and lists all properties as required — the conditions OpenAI strict structured outputs require.

Why must every property be required?

OpenAI strict mode does not support optional properties; the usual workaround is to make the field required but allow null in its type.

Does it validate my schema?

It parses the JSON and reports syntax errors. For deeper validation use the MCP Tool Schema Validator or Structured Output Validator.

Can I use the output with MCP servers?

Yes — pick the MCP target and the schema is emitted under inputSchema, the key MCP clients expect.

Does it work offline and on mobile?

Yes. Once the page has loaded it keeps working without a network connection, and the layout is responsive so it stays usable on phones and tablets.

JSON Schema to AI Tool Schema

Wrap any JSON Schema into a ready-to-use function-calling tool.

Support

Works Offline

Privacy First

No Login

No API

Tool name

Description

Target

Strict mode

JSON Schema

AI tool schema

JSON

{
  "type": "function",
  "function": {
    "name": "search_docs",
    "description": "Search the documentation index.",
    "parameters": {
      "type": "object",
      "properties": {
        "query": {
          "type": "string",
          "description": "Search query"
        },
        "limit": {
          "type": "integer",
          "minimum": 1,
          "maximum": 50
        }
      },
      "required": [
        "query"
      ],
      "additionalProperties": false
    },
    "strict": true
  }
}

About the JSON Schema to AI Tool Schema

Paste a plain JSON Schema, add a tool name and description, and export a valid OpenAI, Anthropic, Gemini or MCP tool definition. Strict mode strips unsupported keywords, forces additionalProperties: false and fills the required array so structured outputs validate first time.

Examples

Search schema

JSON{ "type": "object", "properties": { "query": { "type": "string" } } }

Output

JSONOpenAI tool with strict: true

Keyboard shortcuts

Copy the main outputCtrl / ⌘ + Shift + C
Download the resultCtrl / ⌘ + S
Share this toolCtrl / ⌘ + Shift + S
Reset the inputsAlt + R
Open the tool search paletteCtrl / ⌘ + K

Related tools

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Build function-calling schemas for OpenAI, Claude, Gemini, MCP and the AI SDK.

AI Tool Schema Converter

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Convert function-calling schemas between OpenAI, Anthropic, Gemini and MCP.

LLM Structured Output Validator

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Check that a model's JSON reply matches your JSON Schema.

MCP Tool Schema Validator

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Validate Model Context Protocol tool definitions before you ship them.

MCP Tool Schema Generator

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Generate an MCP, OpenAI or Anthropic tool schema from example arguments.

AI Dataset Deduplicator

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Remove exact and near-duplicate rows from fine-tuning datasets.

Frequently asked questions

Structured data (JSON-LD) that search engines actually use
Most schema.org types have no effect on search results. Here are the ones that do, and how to mark them up correctly.

Version 1.0.0 · Updated 2026-08-15 · Runs entirely in your browser

JSON Schema to AI Tool Schema

About the JSON Schema to AI Tool Schema

Examples

Keyboard shortcuts

Related tools

AI Tool Schema Builder

AI Tool Schema Converter

LLM Structured Output Validator

MCP Tool Schema Validator

MCP Tool Schema Generator

AI Dataset Deduplicator

Frequently asked questions

What does strict mode change?

Why must every property be required?

Does it validate my schema?

Can I use the output with MCP servers?

Does it work offline and on mobile?

Read more