What is an MCP tool schema?

It is the name, description and inputSchema object an MCP server returns from tools/list so a model knows how to call the tool.

How accurate is the inference?

Types, required fields and common string formats are inferred from your example. Review enums, ranges and descriptions before shipping.

Why does strict mode matter?

Setting additionalProperties to false stops models from inventing extra arguments and is required by OpenAI strict function calling.

Is my example sent anywhere?

No. Schema generation runs entirely in your browser.

Is my data uploaded to a server?

No. This tool runs entirely in your browser using standard web APIs, so your input never leaves your device and nothing is logged or stored on our servers.

MCP Tool Schema Generator

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

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Tool definition

Tool name

Target format

Description

Generate field descriptions

Seed enums from string values

Strict (no extra properties)

Example arguments

Paste a sample arguments object — the schema is inferred from it.

Generated tool schema

Properties

Required

Format

MCP

JSON

{
  "name": "get_weather",
  "description": "Get the current weather for a city.",
  "inputSchema": {
    "type": "object",
    "properties": {
      "city": {
        "type": "string",
        "description": "The city."
      },
      "units": {
        "type": "string",
        "description": "The units."
      },
      "include_forecast": {
        "type": "boolean",
        "description": "The include forecast."
      }
    },
    "required": [
      "city",
      "units",
      "include_forecast"
    ],
    "additionalProperties": false
  }
}

About the MCP Tool Schema Generator

Paste a sample arguments object and get a complete tool definition with an inferred JSON Schema: types, integer detection, string formats such as email, uri, uuid and date-time, required fields and optional generated descriptions. Export as an MCP tools/list entry, an OpenAI function tool or an Anthropic tool block.

Examples

Weather tool

JSON{"city":"Berlin","units":"metric"}

Output

{"name":"get_weather","inputSchema":{"type":"object", ...}}

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

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Frequently asked questions

Version 1.0.0 · Updated 2026-08-16 · Runs entirely in your browser