FastMCP Server Development Patterns

I'll help you build robust FastMCP (Model Context Protocol) servers with production-ready patterns. Let me understand your needs:

## YOUR MCP SERVER

- What functionality does your MCP server provide? (file operations, git commands, database access, API integration)
- What tools will your server expose to Claude?
- Will it need subprocess execution? (shell commands, git, etc.)
- Any state management or persistent storage needs?

## EXECUTION ENVIRONMENT

- What's the deployment target? (Docker, local dev, cloud)
- What working directory or workspace structure?
- Any environment variables or configuration needed?
- Security constraints? (allowed commands, path restrictions)

## INTEGRATION REQUIREMENTS

- What external systems will you interact with? (filesystems, APIs, databases)
- Any authentication or API keys to manage?
- Timeout and resource limit requirements?
- Error handling and logging needs?

---

Based on your answers, I'll provide:

## 1. FASTMCP SERVER STRUCTURE

Complete server implementation with:
- **Server initialization** with proper configuration
- **Tool definitions** with clear schemas and descriptions
- **Async handlers** for all operations
- **Error handling** with MCP error types
- **Resource management** for cleanup

## 2. SUBPROCESS EXECUTION PATTERNS

For commands and external processes:
- **Async subprocess execution** with timeout handling
- **Stream capture** for stdout/stderr
- **Exit code handling** and success detection
- **Environment variable management**
- **Working directory control**
- **Timeout and cancellation** support

Example pattern:
```python
async def run_command(command: str, cwd: str, timeout: int):
    # Safe async subprocess with timeout
    # Error handling and result formatting
    # Clean resource cleanup
```

## 3. TOOL IMPLEMENTATION

FastMCP tool patterns for:
- **Input validation** with Pydantic models
- **Authorization checks** before execution
- **Rate limiting** and resource quotas
- **Progress reporting** for long operations
- **Structured responses** with consistent format

## 4. ERROR HANDLING

Comprehensive error management:
- **MCPError types** for different failure modes
- **Timeout handling** with graceful degradation
- **Subprocess errors** with detailed context
- **Validation errors** with helpful messages
- **Resource exhaustion** handling

## 5. SECURITY PATTERNS

Safe execution practices:
- **Command sanitization** to prevent injection
- **Path validation** to prevent traversal
- **Allowed command whitelist** patterns
- **Environment isolation**
- **Resource limits** (memory, CPU, disk)

## 6. DOCKER INTEGRATION

Container deployment:
- Dockerfile with proper base image
- Volume mounting for workspace access
- Environment variable injection
- Health checks and monitoring
- Log aggregation setup

## 7. TESTING & DEBUGGING

- Unit test patterns for async tools
- Integration tests with mock MCP client
- Error scenario testing
- Performance benchmarking
- Logging and debugging strategies

**Example Deliverables**:
- Complete FastMCP server with async subprocess tool
- Error handling for timeouts and failures
- Docker configuration for deployment
- Test suite with async test patterns
- Documentation and usage examples

Tell me what your MCP server needs to do!