Which integrations are available for this server?

Generates UML diagrams in Mermaid format from MSON models, allowing creation of visual system diagrams Creates, validates, and exports UML system models using MSON (Metamodel JavaScript Object Notation) format with support for class, component, deployment, and use case diagrams

How do I use System Designer MCP Server?

1. Click on "Install Server". 2. Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state. 3. In the chat, type @ followed by the MCP server name and your instructions, e.g., "@System Designer MCP Server create a UML class diagram for an e-commerce system with Customer, Order, and Product classes" That's it! The server will respond to your query, and you can continue using it as needed. Here is a step-by-step guide with screenshots.

System Designer MCP Server

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A Model Context Protocol (MCP) server that provides AI agents with tools to create, validate, and export UML system models and System Runtime bundles. Built with a tool-based approach that empowers LLMs to generate complete, executable System Runtime applications.

📚 Documentation

API Reference - Detailed API documentation for all MCP tools
System Runtime Integration Guide - Complete guide to System Runtime bundle creation
Cloudflare Deployment Guide - Deploy to Cloudflare Workers as remote MCP server
CLI Guide - Command-line interface usage and examples
Integration Guide - Platform integration instructions
Examples - Sample models and use cases
Contributing Guide - How to contribute to the project
Code of Conduct - Community guidelines and behavior expectations
Security Policy - Security vulnerability reporting and policies

Features

Core MSON Tools

create_mson_model: Create and validate MSON models from structured data
validate_mson_model: Validate MSON model consistency and completeness
generate_uml_diagram: Generate UML diagrams in PlantUML and Mermaid formats
export_to_system_designer: Export models to System Designer application format

System Runtime Tools

create_system_runtime_bundle: Convert MSON models to complete System Runtime bundles
validate_system_runtime_bundle: Validate System Runtime bundles for correctness and compatibility

Key Capabilities

✅ Tool-Based Architecture: LLMs handle understanding, server handles validation/formatting
✅ Type Safety: Comprehensive Zod schema validation for all inputs and outputs
✅ System Runtime Integration: Full support for System Runtime bundle generation and validation
✅ Bidirectional Relationships: Automatic bidirectional relationship creation
✅ Multiple Inheritance: Support for classes implementing multiple interfaces
✅ Multiple UML Formats: Support for both PlantUML and Mermaid diagram generation
✅ System Designer Integration: Direct export to System Designer macOS application
✅ Comprehensive Testing: 46 tests with 302 expect() calls covering all functionality
✅ Critical Bug Fixes: Resolved SDMCP-001 through SDMCP-005 (property preservation, ID management, validation consistency)
✅ Streamable HTTP Transport: Modern MCP protocol (2025-03-26 specification)
✅ Stateless Operation: Each request creates new server instance
✅ Single Endpoint: Single /mcp endpoint handles all operations
✅ Workers Optimized: Stateless design perfect for Cloudflare Workers

Installation

Prerequisites

Bun JavaScript runtime
Node.js compatibility through Bun

Setup

# Clone the repository git clone https://github.com/chevyphillip/system-designer-mcp.git cd system-designer-mcp # Install dependencies bun install # Build the project bun run build # Run tests bun test

Quick Start

Deployment Options

The System Designer MCP Server can run in two modes:

Local Mode (stdio transport)

Start the local server:

bun run dev

Remote Mode (Cloudflare Workers)

Deploy as a remote MCP server accessible over HTTP with SSE transport:

# Test locally with Wrangler bun run dev:worker # Deploy to Cloudflare Workers bunx wrangler login bun run deploy

Your MCP server will be available at:

https://system-designer-mcp.<your-subdomain>.workers.dev

Note: Replace <your-subdomain> with your actual Cloudflare Workers subdomain.

Key Features:

✅ SSE (Server-Sent Events) transport for remote access
✅ No authentication required (configurable)
✅ All 6 MCP tools available
✅ Returns JSON data directly (no file system)
✅ Automatic session management
✅ CORS support for web clients

See

Usage Examples

Example tool usage:

// Create a MSON model const model = await mcpClient.callTool('create_mson_model', { name: 'Student Management System', type: 'class', description: 'A system for managing students and courses', entities: [ { id: 'student', name: 'Student', type: 'class', attributes: [ { name: 'id', type: 'string', visibility: 'private' }, { name: 'name', type: 'string', visibility: 'public' }, ], methods: [{ name: 'enroll', returnType: 'void', visibility: 'public' }], }, ], relationships: [], }); // Generate UML diagram const diagram = await mcpClient.callTool('generate_uml_diagram', { model: model.content[1].json, format: 'plantuml', }); // Export to System Designer const exported = await mcpClient.callTool('export_to_system_designer', { model: model.content[1].json, filePath: './student_system.json', }); // Create System Runtime bundle const bundle = await mcpClient.callTool('create_system_runtime_bundle', { model: model.content[1].json, version: '1.0.0', }); // Validate System Runtime bundle const validation = await mcpClient.callTool('validate_system_runtime_bundle', { bundle: bundle.content[2].text, // JSON bundle from previous step });

CLI Usage

The server includes a CLI tool for testing and model management:

# Test System Designer integration bun run src/cli.ts test-integration # Export a test model bun run src/cli.ts export-model MyModel "Test model description" # Show configuration bun run src/cli.ts config

See the CLI Guide for detailed usage instructions.

Example MSON Model Structure

{ "id": "student_system", "name": "Student Management System", "type": "class", "description": "A system for managing students and courses", "entities": [ { "id": "student", "name": "Student", "type": "class", "attributes": [ { "name": "id", "type": "string", "visibility": "private" }, { "name": "name", "type": "string", "visibility": "public" } ], "methods": [ { "name": "enroll", "parameters": [ { "name": "course", "type": "Course" } ], "returnType": "void", "visibility": "public" } ] } ], "relationships": [ { "id": "enrollment", "from": "student", "to": "course", "type": "association", "multiplicity": { "from": "1", "to": "0..*" }, "name": "enrolls in" } ] }

Tool Reference

For detailed API documentation, see the API Reference.

Available Tools

create_mson_model - Create and validate MSON models from structured data with automatic ID generation and relationship mapping
validate_mson_model - Validate MSON model consistency and completeness with detailed error messages and relationship validation
generate_uml_diagram - Generate UML diagrams in PlantUML and Mermaid formats
export_to_system_designer - Export models to System Designer application format
create_system_runtime_bundle - Convert MSON models to complete System Runtime bundles with schemas, models, types, behaviors, and components
validate_system_runtime_bundle - Validate System Runtime bundles for correctness and compatibility

Platform Integration

The server can be integrated with various platforms:

Claude Desktop - Native MCP integration
VS Code - Extension development support
Web Applications - React/Node.js integration
CLI Tools - Command-line interface

See the Integration Guide for detailed setup instructions.

Architecture

Modular Structure

The codebase follows SOLID principles with clear separation of concerns:

src/types.ts - TypeScript type definitions for MSON models
src/schemas.ts - Zod validation schemas for all data structures
src/tools.ts - MCP tool registration using modern SDK patterns
src/index.ts - Local MCP server with stdio transport (Node.js/Bun)
src/worker.ts - Remote MCP server with SSE transport (Cloudflare Workers)
src/cli.ts - Command-line interface for testing and integration
src/integration/ - System Designer app integration
src/transformers/ - MSON to System Runtime transformation logic
src/validators/ - System Runtime bundle validation logic

Modern MCP SDK Patterns

The server uses the modern MCP TypeScript SDK (v1.18.2) patterns:

server.registerTool() - Modern tool registration API (not legacy server.tool())
Zod Input Schemas - Type-safe input validation with Zod schema shapes
Title Metadata - Each tool includes a title field for better UX
Type Inference - Handler methods use Zod-inferred types for parameters

Tool-Based Approach

This server uses a tool-based architecture that:

Empowers LLMs: The LLM handles understanding requirements and creating structured data
Validates Input: Server validates structured input using comprehensive Zod schemas
Processes Efficiently: Simple, fast processing without complex parsing logic
Exports Flexibly: Multiple output formats for different use cases

Benefits Over Parser-Based Approaches

Simplicity: No complex NLP parsing to maintain
Flexibility: Works with any domain the LLM understands
Reliability: Fewer moving parts, less error-prone
Performance: Faster validation and processing
Extensibility: Easy to add new tools and features

Development

Running Tests

# Run all tests bun test # Run tests in watch mode bun test --watch

Building

# Build for production bun run build # Start production server bun start

Code Structure

src/ ├── types.ts # TypeScript type definitions for MSON models ├── schemas.ts # Zod validation schemas for all data structures ├── tools.ts # MCP tool registration using modern SDK patterns ├── index.ts # Local MCP server (stdio transport) ├── worker.ts # Remote MCP server (SSE transport for Workers) ├── cli.ts # Command-line interface ├── integration/ │ └── system-designer.ts # System Designer app integration ├── transformers/ │ └── system-runtime.ts # MSON to System Runtime transformation └── validators/ └── system-runtime.ts # System Runtime bundle validation test/ └── tool-based.test.ts # Comprehensive test suite docs/ ├── API-REFERENCE.md # Detailed API documentation ├── CLI-GUIDE.md # CLI usage guide ├── INTEGRATION-GUIDE.md # Platform integration guide └── SYSTEM-RUNTIME-INTEGRATION-GUIDE.md # System Runtime guide examples/ ├── banking-system.json # Sample banking system model ├── banking-system-plantuml.puml # PlantUML output example ├── banking-system-mermaid.md # Mermaid output example └── README.md # Example documentation CLOUDFLARE_DEPLOYMENT.md # Cloudflare Workers deployment guide test-worker.sh # Automated testing script for Workers wrangler.toml # Cloudflare Workers configuration

Integration with System Designer

The server exports models in a format compatible with the System Designer macOS application:

File Export: Models are saved as JSON files
Automatic Integration: Files can be imported directly into System Designer
Format Compatibility: Uses MSON (Metamodel JavaScript Object Notation) format

Recent Changes & Improvements

Latest Updates (v1.0.0)

🎯 Critical Bug Fixes (SDMCP-001-005): Resolved property preservation, ID mapping, validation consistency, and bundle compatibility issues
🔧 Enhanced Error Messages: Added detailed, actionable error messages with specific fix suggestions and examples
🛡️ Relationship Validation: Proactive validation prevents orphaned references with clear guidance
🔄 Flexible Input Handling: Support for both 'properties' and 'attributes' in entity definitions
📋 Comprehensive Bug Reports: Detailed documentation of all issues and resolutions in docs/BUG_REPORTS.md
🆕 System Runtime Tools: Added complete System Runtime bundle creation and validation functionality

Previous Features

🏗️ Modular Architecture: Complete refactoring for SOLID principles compliance
🧪 Enhanced Testing: 46 tests with 302 assertions covering all functionality including edge cases
🚀 Cloudflare Workers Support: Remote MCP server deployment with modern JSON-RPC transport
🔄 Modern MCP SDK: Updated to latest MCP TypeScript SDK (v1.18.2) patterns
📊 Documentation: Complete API reference, integration guides, and deployment documentation

Contributing

We welcome contributions! Please see our Contributing Guide for details on:

Setting up the development environment
Running tests and code quality checks
Code style guidelines
Submitting pull requests
Reporting issues

License

MIT License - see LICENSE file for details.

Acknowledgments

Model Context Protocol (MCP) for the tool integration framework
System Designer for the target macOS application
Zod for type-safe validation
Bun for the fast JavaScript runtime