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Beyond MCP Server Examples

This directory contains a comprehensive set of example applications that demonstrate the progressive complexity of dependency management and plugin workflows in Beyond MCP Server. Each example builds upon the previous one, providing a clear learning path for users.

📚 Learning Progression

The examples are designed to be studied in order, with each demonstrating increasingly sophisticated features:

1️⃣ 1-simple - Zero Custom Dependencies + Basic Plugin Tools

Complexity: ⭐ Beginner
Features: Basic plugin system, simple tools, minimal configuration
Learning Focus: "How to get started with minimal setup"

  • ✅ Zero custom dependencies (uses library defaults)
  • ✅ Plugin discovery with basic utility tools
  • ✅ Environment configuration fundamentals
  • ✅ STDIO and HTTP transport support

Tools Demonstrated:

  • current_datetime - Shows basic data retrieval
  • get_system_info - Shows system integration
  • validate_json - Shows data validation

Key Learning Points:

  • Plugin creation and discovery
  • Basic tool development patterns
  • Environment variable configuration
  • AppServer.create() with minimal setup

2️⃣ 2-plugin-workflows - Zero Custom Dependencies + Plugin Workflows

Complexity: ⭐⭐ Intermediate
Features: Workflows vs tools, multi-step processes, state management
Learning Focus: "When and how to use workflows vs simple tools"

  • ✅ Same infrastructure approach as simple example
  • ✅ Plugin containing both tools AND workflows
  • ✅ Multi-step business process orchestration
  • ✅ Workflow state management and error recovery

Workflows Demonstrated:

  • Data Processing Pipeline: Multi-step data transformation
  • File Management Workflow: Create → Validate → Process → Archive
  • Content Generation Workflow: Plan → Generate → Review → Publish

Key Learning Points:

  • When to use workflows vs simple tools
  • Multi-step process orchestration
  • State management and error handling
  • Workflow step tracking and audit trails

3️⃣ 3-plugin-api-auth - Custom API Client + OAuth Consumer

Complexity: ⭐⭐⭐ Advanced
Features: Third-party API integration, OAuth authentication, custom dependencies
Learning Focus: "How to integrate with external APIs requiring authentication"

  • ✅ Custom dependency creation for API integration
  • ✅ OAuth consumer for third-party authentication
  • ✅ Integration between library and business components
  • ✅ Real-world API integration patterns

Integration Components:

  • ExampleOAuthConsumer - Custom OAuth consumer implementation
  • ExampleApiClient - Third-party API client with authentication
  • ExampleDependencies - Dependency injection and configuration

Key Learning Points:

  • Custom dependency creation patterns
  • OAuth consumer implementation
  • API client architecture
  • Library + business component integration

4️⃣ 4-manual-deps - Full Custom Dependency Override

Complexity: ⭐⭐⭐⭐ Expert
Features: Complete infrastructure control, advanced customization
Learning Focus: "Advanced customization and infrastructure control"

  • ✅ Override all default library dependencies
  • ✅ Complete control over infrastructure components
  • ✅ Advanced configuration and customization patterns
  • ✅ Manual tool and workflow registration (no plugin discovery)

Advanced Features:

  • Custom transport configuration
  • Advanced KV storage setup
  • Manual tool/workflow registration
  • Complete dependency injection control

Key Learning Points:

  • Full infrastructure customization
  • Advanced dependency injection patterns
  • Manual registration vs plugin discovery
  • Expert-level configuration control

🎯 Example Structure Standards

Each example follows a consistent structure to aid learning:

{N}-example-name/
├── README.md                    # Example-specific documentation
├── main.ts                      # Entry point with AppServer setup
├── .env.example                 # Environment configuration template
├── .env                         # Local environment (gitignored)
├── deno.jsonc                   # Deno configuration
├── instructions.md              # Step-by-step setup instructions (for humans)
├── mcp_server_instructions.md   # LLM context instructions (for AI models)
│── src/
│   ├── plugins/          # Self-contained plugin implementations
│   │   ├── {Plugin}.ts   # Plugin definition and exports
│   │   ├── tools/        # Tool implementations (when applicable)
│   │   ├── workflows/    # Workflow implementations (when applicable)
│   │   └── types/        # Plugin-specific types
│   ├── config/           # Configuration and dependencies (3+ only)
│   ├── auth/             # Authentication components (3+ only)
│   └── api/              # API clients (3+ only)
└── tests/                # Example-specific demonstration tests
	├── tools/            # Tool testing demonstrations
	└── workflows/        # Workflow testing demonstrations

🤖 MCP Server Instructions (LLM Context)

Each example includes mcp_server_instructions.md that provides essential context for AI models using the MCP server. These instructions are automatically loaded by the server and help LLMs understand:

Purpose & Importance

  • Tool Usage: When and how to use specific tools and workflows
  • Parameter Requirements: Required vs optional parameters and validation rules
  • Authentication: OAuth flows and security requirements (examples 3-4)
  • Error Handling: Common issues and recovery strategies
  • Best Practices: Optimal usage patterns for complex operations

Instructions vs Documentation

  • instructions.md: Step-by-step setup guide for humans
  • mcp_server_instructions.md: Usage context for LLM models

Automatic Loading

The server automatically loads instructions using this priority order:

  1. MCP_SERVER_INSTRUCTIONS environment variable (direct content)
  2. MCP_INSTRUCTIONS_FILE environment variable (file path)
  3. mcp_server_instructions.md in project root (default location)
  4. Built-in generic fallback instructions (always available)

Customization

You can customize instructions for your specific use case:

# Option 1: Direct environment variable
MCP_SERVER_INSTRUCTIONS="Custom instructions for your server..."

# Option 2: Custom file path  
MCP_INSTRUCTIONS_FILE="./config/custom-instructions.md"

# Option 3: Default file (no configuration needed)
# Just place your instructions in: ./mcp_server_instructions.md

💡 Pro Tip: Study each example's instructions to understand how complexity evolves from simple tools to OAuth-enabled workflows.

⚠️ Critical Implementation Patterns

inputSchema Configuration (IMPORTANT)

When defining tool inputSchema, use a plain JavaScript object with Zod schemas as values:

// ✅ CORRECT: Plain object with Zod schema values
inputSchema: {
  json_string: z.string().describe('JSON string to validate'),
  format: z.boolean().default(true).describe('Whether to format the JSON'),
  indent: z.number().int().min(0).max(8).default(2).describe('Indentation spaces'),
}

// ❌ INCORRECT: Do NOT wrap with z.object()
inputSchema: z.object({
  json_string: z.string().describe('JSON string to validate'),
  // ... causes type and runtime errors
})

Why This Matters:

  • The MCP library expects plain object structure for inputSchema
  • Using z.object() wrapper causes type and runtime errors
  • All examples follow the correct pattern shown above
  • Always include .describe() calls for MCP protocol documentation

🧪 Testing Demonstration

Each example includes demonstration tests that show users how to test their tools and workflows:

Tool Testing Patterns

  • Registration Testing: Verify tools are properly registered
  • Parameter Validation: Test input validation and error handling
  • Execution Testing: Test tool logic and response formatting
  • Context Testing: Test user context extraction and logging
  • Integration Testing: Test with realistic scenarios

Workflow Testing Patterns

  • Parameter Validation: Test Zod schema validation
  • Execution Flow: Test multi-step workflow execution
  • State Management: Test resource tracking and context management
  • Error Handling: Test error classification and recovery
  • Step Tracking: Test completed/failed step management

Testing Tools Used

  • Mock Services: Mock API clients, databases, external services
  • Spy Functions: Monitor function calls and verify behavior
  • Test Helpers: Reusable test utilities and fixtures
  • Integration Tests: End-to-end testing with realistic scenarios

🚀 Getting Started

  1. Start with 1-simple to understand basic concepts
  2. Progress through each example in numerical order
  3. Run the tests to see testing patterns in action
  4. Modify and experiment with each example to deepen understanding
  5. Use as templates for your own MCP server implementations

📖 Documentation Features

Each example includes:

  • ✅ Step-by-step tutorials with clear instructions
  • ✅ Architecture explanations showing component relationships
  • ✅ Common pitfalls and troubleshooting guidance
  • ✅ Migration paths showing how to evolve from simpler to more complex setups
  • ✅ Best practices and recommended patterns
  • ✅ Testing demonstrations showing how to validate implementations

🛠️ Development Workflow

For each example:

# Navigate to example directory
cd examples/{N}-example-name

# Copy environment template
cp ../.env.example .env

# Edit configuration
vim .env

# Run the example
deno run --allow-all main.ts

# Run tests (demonstration purposes)
deno test --allow-all tests/

🎯 Success Metrics

These examples are successful if they:

  • ✅ Reduce Learning Curve: Clear progression from simple to complex
  • ✅ Demonstrate Best Practices: Show recommended patterns and architectures
  • ✅ Provide Working Code: All examples run successfully out of the box
  • ✅ Enable Rapid Development: Serve as templates for real implementations
  • ✅ Show Testing Patterns: Demonstrate how to validate implementations

🔄 Migration Between Examples

Users can evolve their implementations by following the progression:

  • 1→2: Add workflows to existing simple tool setup
  • 2→3: Add external API integration and authentication
  • 3→4: Gain full control over infrastructure dependencies
  • Any→Production: Use learned patterns in production applications

These examples are the primary way for users to learn Beyond MCP Server. They demonstrate not just how to use the library, but when and why to use different approaches.