JSON Schema Generator

Overview

Creates JSON Schema definitions for data validation and API documentation.

Instructions

When generating JSON Schema:

1. Analyze the data structure or requirements
2. Determine types for each field (string, number, object, array, etc.)
3. Add constraints: required fields, patterns, min/max values
4. Include descriptions for documentation
5. Set appropriate $schema version (draft-07 recommended)

Schema Components

Basic Types

• string - Text values
• number / integer - Numeric values
• boolean - True/false
• object - Nested structures
• array - Lists of items
• null - Null values

Common Constraints

• required - Mandatory fields
• minLength / maxLength - String length
• minimum / maximum - Number bounds
• pattern - Regex validation
• enum - Allowed values
• format - Semantic formats (email, uri, date-time)

Examples

Example: User Schema

Input: "Create a schema for a user with name, email, age, and optional phone"

Output:

{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "title": "User",
  "type": "object",
  "required": ["name", "email", "age"],
  "properties": {
    "name": {
      "type": "string",
      "minLength": 1,
      "maxLength": 100,
      "description": "User's full name"
    },
    "email": {
      "type": "string",
      "format": "email",
      "description": "User's email address"
    },
    "age": {
      "type": "integer",
      "minimum": 0,
      "maximum": 150,
      "description": "User's age in years"
    },
    "phone": {
      "type": "string",
      "pattern": "^\\+?[1-9]\\d{1,14}$",
      "description": "Optional phone number in E.164 format"
    }
  },
  "additionalProperties": false
}

Guidelines

Do

• Always include $schema declaration
• Add descriptions for all properties
• Use additionalProperties: false for strict validation
• Prefer specific formats over loose patterns
• Use required array for mandatory fields

Don't

• Use overly permissive types (avoid {} or true)
• Skip validation constraints on user input
• Mix draft versions in same schema
• Forget to handle nullable fields explicitly