MCP - Model Context Protocol: Khi AI biết 'gọi ngoại binh'

// Tool calling cũ: Functions hardcoded
const tools = [calculate, getWeather, sendEmail]; // ← Cố định!

// MCP: AI tự discovery tools từ servers
const mathServer = new MCPServer("math-tools");
const weatherServer = new MCPServer("weather-api");  
const emailServer = new MCPServer("email-service");

// AI: "Hmm, tôi cần tools gì nhỉ?"
const availableTools = await discoverAllTools(); // ← Dynamic!

// Server expose tools
server.registerTool("calculate", {
  description: "Tính toán biểu thức toán học",
  inputSchema: { expression: z.string() }
}, async ({ expression }) => {
  return { content: [{ type: "text", text: eval(expression) }] };
});

// AI gọi tool
await client.callTool('calculate', { expression: '2 + 2' });
// → "4"

// Server expose resources
await client.readResource('file:///project/README.md');
await client.readResource('database://users/schema');
await client.readResource('api://swagger.json');

// Math server biết cách prompt AI solve math problems
server.registerPrompt("solve-equation", {
  argsSchema: { equation: z.string(), method: z.string() }
}, ({ equation, method }) => ({
  messages: [{
    role: "user",
    content: {
      type: "text", 
      text: `
Solve this equation step by step: ${equation}

Use ${method} method. Show:
1. Original equation
2. Step-by-step solution  
3. Final answer
4. Verification

Remember to explain each algebraic manipulation clearly.
      `
    }
  }]
}));

// AI: "Tôi muốn biết bạn có gì?"
const tools = await client.listTools();
const resources = await client.listResources();
const prompts = await client.listPrompts();

// Server: "Tôi có những này đây!"
// Tools: [calculate, send_email, query_db]
// Resources: [file://, database://, config://]
// Prompts: [solve-equation, debug-code, optimize-query]

// AI quyết định: "Tôi cần tính toán!"
const result = await client.callTool('calculate', {
  expression: 'Math.sqrt(16) + Math.PI'
});
// → "7.141592653589793"

// AI: "Tôi cần đọc file!"
const content = await client.readResource('file:///README.md');
// → File content

// AI: "Tôi cần prompt hay để debug!"
const debugPrompt = await client.getPrompt('debug-code', {
  error: 'TypeError: Cannot read property of undefined',
  code: '...'
});
// → Structured prompt với debugging best practices

// Server thông báo: "Tôi có tools mới!"
server.notify('tools/list_changed');

// AI tự động refresh và discover tools mới
const newTools = await client.listTools();

const client = new MCPClient();

// Kết nối multiple servers
await client.connect('node', ['./file-server.js']);     // File operations
await client.connect('node', ['./db-server.js']);       // Database access
await client.connect('node', ['./git-server.js']);      // Git operations
await client.connect('node', ['./api-server.js']);      // API testing

// Bây giờ AI có thể:
// 1. List files trong project
const files = await client.callTool('list_files', {pattern: '*.ts'});

// 2. Đọc source code  
const code = await client.readResource('file:///src/main.ts');

// 3. Query database để hiểu data structure
const schema = await client.callTool('describe_table', {table: 'users'});

// 4. Check git history
const commits = await client.callTool('git_log', {limit: 10});

// 5. Test API endpoints
const apiResult = await client.callTool('test_endpoint', {
  url: '/api/users', method: 'GET'
});

// 6. Sử dụng specialized prompts
const codeReview = await client.getPrompt('code-review', {
  code: code, framework: 'React', type: 'component'
});

// Dễ dàng thêm/bớt capabilities
await addServer('./new-awesome-server.js');
await removeServer('./old-server.js');
// AI tự động adapt với tools mới!

// Local servers
await client.connect('node', ['./local-server.js']);

// Remote servers  
await client.connect('http://api.example.com/mcp');

// Server có thể update capabilities runtime
server.addTool('new_feature', ...);
server.notify('tools/list_changed');
// AI tự động biết và sử dụng ngay!

import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";

const server = new McpServer({
  name: "my-awesome-server",
  version: "1.0.0"
});

// Add a calculator tool
server.registerTool("calculate", {
  title: "Calculator",
  description: "Evaluate mathematical expressions",
  inputSchema: { expression: z.string() }
}, async ({ expression }) => ({
  content: [{ type: "text", text: String(eval(expression)) }]
}));

// Add a resource  
server.registerResource("config", "config://app", {
  title: "App Configuration"
}, async () => ({
  contents: [{ 
    uri: "config://app",
    text: JSON.stringify({ env: "production", debug: false })
  }]
}));

// Add a prompt
server.registerPrompt("debug-helper", {
  title: "Debug Assistant",
  argsSchema: { error: z.string(), code: z.string() }
}, ({ error, code }) => ({
  messages: [{
    role: "user",
    content: { 
      type: "text",
      text: `Help me debug this error:\n\nError: ${error}\n\nCode:\n${code}\n\nProvide step-by-step debugging approach.`
    }
  }]
}));

// Start server
const transport = new StdioServerTransport();
await server.connect(transport);
console.log("🚀 MCP Server running!");

import { MCPClient } from './client.js';

const client = new MCPClient();
await client.connect('node', ['./my-server.js']);
const result = await client.callTool('calculate', { expression: '2 + 2' });