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JSON Schema Validator MCP Server

by EienWolf
GitHub
Python
  • Apple
  • Linux
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JSON Schema Validator MCP Server

A comprehensive JSON Schema validation server implementing the Model Context Protocol (MCP) with support for JSON Schema Draft 2020-12, external references, and real-time streaming validation.

🚀 Features

  • JSON Schema Draft 2020-12 Support: Full compliance with the latest JSON Schema specification
  • External Reference Resolution: Automatic resolution of external schema references via HTTP/HTTPS, database, or local files
  • Dual Server Architecture:
    • MCP Server for stdio communication with AI assistants
    • SSE Server for web clients with real-time streaming
  • Schema Management: Complete CRUD operations for schema collections
  • Data Storage Flexibility: PostgreSQL database with local file fallback
  • Schema Generation: Automatic JSON Schema generation from sample JSON data
  • Docker Support: Containerized deployment ready

🏗️ Architecture

Core Components

  • MCP Server (mcp_server.py): Primary server for AI assistant integration
  • SSE Server (sse_server.py): HTTP server with Server-Sent Events for web clients
  • Validation Engine (tools/JSONSchemaValidator.py): JSON Schema Draft 2020-12 validator
  • Data Manager (utils/DataManager.py): Multi-source data resolution with fallback strategy
  • Schema Generator (utils/SchemaGenerator.py): Automatic schema generation from JSON data

Data Resolution Strategy

  1. PostgreSQL Database (schemas/data_storage tables)
  2. Local Files (final fallback)

📦 Installation

Prerequisites

  • Python 3.8+
  • PostgreSQL (optional, for database storage)

Quick Start

  1. Clone the repository
    git clone https://github.com/EienWolf/jsonshema_mcp.git cd jsonschema_mcp
  2. Install dependencies
    pip install -r requirements.txt
  3. Run the MCP server
    python mcp_server.py
  4. Run the SSE server (optional)
    python sse_server.py

🔧 Configuration

Environment Variables

Create a .env file:

# PostgreSQL Configuration POSTGRES_HOST=localhost POSTGRES_PORT=5432 POSTGRES_DATABASE=jsonschema_mcp POSTGRES_USER=your_username POSTGRES_PASSWORD=your_password # Schema Management POSTGRES_AUTO_CREATE_SCHEMA=true # Auto-create tables if missing POSTGRES_AUTO_RESET=false # WARNING: Drops all data!

🛠️ Available MCP Tools

Validation Tools

  • validate_json_schema: Direct validation with provided schema
  • validate_json_from_collections: Validation using stored schemas
  • get_validation_info: Validator capabilities and information

Schema Management Tools

  • add_update_schema: Add or update schemas in collections
  • delete_schema: Delete schemas from collections
  • get_schema: Retrieve schema content
  • list_schemas: List all available schemas
  • generate_schema: Generate schema from JSON data

🐳 Docker Deployment

Build and Run

# Build image docker build -t jsonschema-mcp-server:1.0.0 . # Run container docker run -i jsonschema-mcp-server:1.0.0 # Run with persistent schema storage docker run -i -v ./schemas:/app/.schemas jsonschema-mcp-server:1.0.0

Docker Features

  • Multi-stage build optimization
  • Non-root user security
  • Health check monitoring
  • Volume support for data persistence
  • Automatic dependency management

🤖 MCP Server Configuration

Claude Desktop Integration

Method 1: Direct Python Execution

Add to your Claude Desktop configuration file:

Windows: %APPDATA%\Claude\claude_desktop_config.json macOS: ~/Library/Application Support/Claude/claude_desktop_config.json Linux: ~/.config/Claude/claude_desktop_config.json

{ "mcpServers": { "jsonschema-validator": { "command": "python", "args": ["C:\\path\\to\\jsonschema_mcp\\mcp_server.py"], "env": { "POSTGRES_HOST": "localhost", "POSTGRES_PORT": "5432", "POSTGRES_DATABASE": "jsonschema_mcp", "POSTGRES_USER": "your_username", "POSTGRES_PASSWORD": "your_password" } } } }

Linux/macOS Example:

{ "mcpServers": { "jsonschema-validator": { "command": "python3", "args": ["/path/to/jsonschema_mcp/mcp_server.py"], "env": { "POSTGRES_HOST": "localhost", "POSTGRES_PORT": "5432", "POSTGRES_DATABASE": "jsonschema_mcp", "POSTGRES_USER": "your_username", "POSTGRES_PASSWORD": "your_password" } } } }
Method 2: Docker Container
{ "mcpServers": { "jsonschema-validator": { "command": "docker", "args": [ "run", "-i", "--rm", "-v", "./schemas:/app/.schemas", "-e", "POSTGRES_HOST=host.docker.internal", "-e", "POSTGRES_PORT=5432", "-e", "POSTGRES_DATABASE=jsonschema_mcp", "-e", "POSTGRES_USER=your_username", "-e", "POSTGRES_PASSWORD=your_password", "jsonschema-mcp-server:1.0.0" ] } } }

GitHub Copilot Integration

Method 1: Direct Python Execution

Create or update your MCP configuration file:

File: ~/.mcp/config.json (Linux/macOS) or %USERPROFILE%\.mcp\config.json (Windows)

{ "servers": { "jsonschema-validator": { "command": "python", "args": ["C:\\path\\to\\jsonschema_mcp\\mcp_server.py"], "env": { "POSTGRES_HOST": "localhost", "POSTGRES_PORT": "5432", "POSTGRES_DATABASE": "jsonschema_mcp", "POSTGRES_USER": "your_username", "POSTGRES_PASSWORD": "your_password" } } } }

Linux/macOS Example:

{ "servers": { "jsonschema-validator": { "command": "python3", "args": ["/path/to/jsonschema_mcp/mcp_server.py"], "env": { "POSTGRES_HOST": "localhost", "POSTGRES_PORT": "5432", "POSTGRES_DATABASE": "jsonschema_mcp", "POSTGRES_USER": "your_username", "POSTGRES_PASSWORD": "your_password" } } } }
Method 2: Docker Container
{ "servers": { "jsonschema-validator": { "command": "docker", "args": [ "run", "-i", "--rm", "-v", "./schemas:/app/.schemas", "-e", "POSTGRES_HOST=host.docker.internal", "-e", "POSTGRES_PORT=5432", "-e", "POSTGRES_DATABASE=jsonschema_mcp", "-e", "POSTGRES_USER=your_username", "-e", "POSTGRES_PASSWORD=your_password", "jsonschema-mcp-server:1.0.0" ] } } }

Configuration Notes

  1. Database Configuration:
    • Environment variables are optional
    • Server automatically falls back to local file storage if database is unavailable
    • For file-only mode, omit all POSTGRES_* environment variables
  2. Path Requirements:
    • Use absolute paths for mcp_server.py
    • Ensure Python is in your system PATH
    • For Docker, ensure the image is built: docker build -t jsonschema-mcp-server:1.0.0 .
  3. Permissions:
    • Ensure the server has write permissions to the schemas directory
    • For Docker on Windows, use WSL2 backend for better volume mounting
  4. Testing Configuration:
    # Test direct execution python mcp_server.py # Test Docker execution docker run -i jsonschema-mcp-server:1.0.0
  5. File-Only Configuration (No Database):
    { "mcpServers": { "jsonschema-validator": { "command": "python", "args": ["C:\\path\\to\\jsonschema_mcp\\mcp_server.py"] } } }

🌐 Web Client

The repository includes a complete web client (client_example.html) demonstrating:

  • Real-time validation with Server-Sent Events
  • Schema management interface
  • Interactive testing environment
  • Progress tracking and error reporting

🔒 Security Features

  • Input Validation: Schema ID format validation with Linux path requirements
  • Path Security: Prevention of directory traversal attacks
  • Confirmation Requirements: Explicit confirmation for destructive operations
  • Error Handling: Detailed error messages without sensitive information exposure
  • Non-root Execution: Docker containers run as non-privileged user

📋 Requirements

  • jsonschema>=4.25.0 - JSON Schema validation
  • mcp>=1.0.0 - Model Context Protocol
  • psycopg2-binary>=2.9.0 - PostgreSQL adapter
  • fastapi>=0.104.0 - SSE server framework
  • uvicorn>=0.24.0 - ASGI server
  • pydantic>=2.5.0 - Data validation
  • ruff>=0.8.0 - Code linting and formatting

🆘 Troubleshooting

Common Issues

  1. Database Connection Failed
    • Check PostgreSQL is running
    • Verify credentials in .env
    • Server falls back to file storage automatically
  2. Permission Denied
    • Ensure write permissions for .schemas directory
    • Check Docker volume mounting
  3. Schema Not Found
    • Verify schema ID format (must end with .json)
    • Check schema exists with list_schemas tool

🗺️ Roadmap

See our ROADMAP.md for planned features and future development directions, including DXT package integration, enhanced schema generation, and AI-powered capabilities.

📄 License

This project is licensed under a Custom Non-Commercial License. See the LICENSE file for details.

🙏 Acknowledgments

  • Built on the Model Context Protocol (MCP) specification
  • Uses the jsonschema library for validation
  • Inspired by modern API design patterns
  • Designed for integration with AI assistants

📞 Support

For issues, questions, or contributions:

  1. Check the troubleshooting section above
  2. Review existing issues and documentation
  3. Create a detailed issue report with:
    • Error messages
    • Steps to reproduce
    • Environment details
    • Expected vs actual behavior

Made with ❤️ for the AI and developer community

This server cannot be installed

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security - not tested
F
license - not found
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quality - not tested

How are these scores calculated?

A comprehensive server that enables validation of JSON data against JSON Schema Draft 2020-12, with support for external references, schema management, and real-time streaming validation.

  1. 🚀 Features
    1. 🏗️ Architecture
      1. Core Components
      2. Data Resolution Strategy
    2. 📦 Installation
      1. Prerequisites
      2. Quick Start
    3. 🔧 Configuration
      1. Environment Variables
    4. 🛠️ Available MCP Tools
      1. Validation Tools
      2. Schema Management Tools
    5. 🐳 Docker Deployment
      1. Build and Run
      2. Docker Features
    6. 🤖 MCP Server Configuration
      1. Claude Desktop Integration
      2. GitHub Copilot Integration
      3. Configuration Notes
    7. 🌐 Web Client
      1. 🔒 Security Features
        1. 📋 Requirements
          1. 🆘 Troubleshooting
            1. Common Issues
          2. 🗺️ Roadmap
            1. 📄 License
              1. 🙏 Acknowledgments
                1. 📞 Support

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