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Developer & data · By AIXpress

MCP Tool Definition Generator

Create an MCP tool definition with a valid name, description, supported JSON Schema input contract, and optional output contract.

MCP server developers drafting tool metadata and parameter schemas.

Free to use. Your inputs are processed in this browser and are not included in usage analytics.

Describe its task, expected inputs, and resulting outcome.

The input schema must declare type object.

Leave empty to omit an output schema.

How to use mcp tool definition generator

  1. Name the tool and describe the concrete task it performs.
  2. Provide an object input schema and optionally an output schema using the supported subset.
  3. Copy the definition into your MCP server and implement its handler separately.

What to know about the result

  • Supported validation keywords: type, properties, required, additionalProperties, items, enum, const, minimum, maximum, minLength, maxLength, minItems, and maxItems. Boolean schemas and annotations are supported.
  • Only JSON Schema 2020-12 is supported. Unsupported keywords, including $ref, pattern, format, and combinators, are rejected everywhere. This is a subset validator, not a complete JSON Schema implementation.
  • The generated definition does not implement or register a tool. Default JSON Schema dialect is 2020-12, as specified by MCP.
  • MCP tools specification: https://modelcontextprotocol.io/specification/2026-07-28/server/tools

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