mcp-devtools / rules

---
description: MCP Server Implementation Guidelines
globs: packages/*/src/index.ts
alwaysApply: true
---

# MCP Server Implementation Guidelines

When implementing a new MCP server or updating an existing one, follow these guidelines:

@file packages/jira/src/index.ts
@file .cursor/rules/core-libraries-usage.mdc
@file .cursor/rules/typescript-style.mdc

## Server Setup

```typescript
import { createMcpServer } from "@modelcontextprotocol/server";
import { registerTool1 } from "./tools/tool1";
import { registerTool2 } from "./tools/tool2";
// Import more tools as needed

// Create configuration with proper error handling
const getConfig = (): Config => {
  const required = ["REQUIRED_ENV_VAR1", "REQUIRED_ENV_VAR2"];
  for (const env of required) {
    if (!process.env[env]) {
      console.error(`Missing required environment variable: ${env}`);
      process.exit(1);
    }
  }

  return {
    var1: process.env.REQUIRED_ENV_VAR1,
    var2: process.env.REQUIRED_ENV_VAR2,
    optionalVar: process.env.OPTIONAL_ENV_VAR || "default",
  };
};

// Initialize server
const initServer = async () => {
  try {
    const config = getConfig();
    const server = createMcpServer();

    // Register all tools
    registerTool1(server);
    registerTool2(server);
    // Register more tools

    // Start the server
    server.start();
    console.log("MCP server started successfully");
  } catch (error) {
    console.error("Failed to start MCP server:", error);
    process.exit(1);
  }
};

// Start the server
initServer();
```

## Guidelines

1. **Environment Variables**

   - Validate all required environment variables at startup
   - Provide sensible defaults for optional variables
   - Document all environment variables in README

2. **Error Handling**

   - Implement proper error handling for server initialization
   - Log meaningful error messages
   - Exit with non-zero code on critical errors

3. **Tool Registration**

   - Register each tool from its own module
   - Keep registration code organized and maintainable
   - Use consistent patterns across all tools

4. **Logging**

   - Log server start/stop events
   - Include appropriate context in logs
   - Avoid logging sensitive information

5. **Server Configuration**
   - Centralize configuration in one place
   - Validate configuration at startup
   - Use typed configuration objects