Gmail MCP Server

# MCP Gmail Server - Copilot Instructions This project implements a minimal Model Context Protocol (MCP) server for sending emails through Gmail. ## Project Overview - **Language**: TypeScript (Node.js) - **Framework**: MCP TypeScript SDK (@modelcontextprotocol/sdk) - **Email Provider**: Gmail via Nodemailer - **Transport**: STDIO (for local MCP client connections) - **Architecture**: Single tool server with structured input/output ## Key Components ### Core Files - `src/index.ts` - Main MCP server implementation with send_email tool - `package.json` - Dependencies and build scripts - `tsconfig.json` - TypeScript configuration - `.env.example` - Environment variables template ### MCP Configuration - `.well-known/mcp.json` - Server discovery manifest - `.vscode/mcp.json` - VS Code MCP client configuration - `demo.sh` - Manual testing script for MCP protocol ### Build System - `npm run build` - Compiles TypeScript to build/ - `npm start` - Runs the compiled server - `npm run dev` - Development mode with tsx ## MCP Implementation Details This server follows MCP specification by: 1. **Tool Registration**: Exposes `send_email` tool with Zod schema validation 2. **STDIO Transport**: Uses StdioServerTransport for client communication 3. **Structured Output**: Returns JSON with success/error states and metadata 4. **Environment Security**: Credentials loaded from env vars, never hardcoded 5. **Error Handling**: Comprehensive logging and structured error responses ## Development Guidelines - Use the MCP TypeScript SDK for all protocol interactions - Follow the existing error handling patterns - Log all operations to stderr (stdout reserved for MCP protocol) - Validate all inputs with Zod schemas - Return structured output with both text and structured content - Never hardcode credentials - always use environment variables ## Testing - Use `./demo.sh` for manual protocol testing - Use MCP Inspector: `npx @modelcontextprotocol/inspector node build/index.js` - Integrate with Claude Desktop or other MCP clients ## Dependencies - `@modelcontextprotocol/sdk` - MCP protocol implementation - `nodemailer` - Email sending functionality - `zod` - Runtime type validation and schema definition - `dotenv` - Environment variable management - `typescript` + `tsx` - TypeScript development tools