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// MCP Server 示例：一个简单的数据库查询工具
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import { Server } from '@modelcontextprotocol/sdk'
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import { Database } from 'libsql'
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const server = new Server('database-agent', {
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  capabilities: {
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    tools: {
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      // 注册工具
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      query_database: {
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        description: '对数据库执行 SQL 查询',
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        parameters: {
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          type: 'object',
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          properties: {
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            sql: { type: 'string', description: 'SQL 查询语句' },
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            params: {
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              type: 'array',
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              items: { type: 'string' },
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              description: 'SQL 参数（可选）'
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            }
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          },
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          required: ['sql']
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        },
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        // 工具的实现逻辑
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        handler: async ({ sql, params }) => {
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          const db = new Database('file:./local.db')
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          const result = await db.execute(sql, params ?? [])
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          return {
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            content: [{
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              type: 'text',
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              text: JSON.stringify(result.rows, null, 2)
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            }]
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          }
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        }
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      }
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    }
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  }
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})
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// 启动 MCP 服务器
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server.listen(3001)

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┌─────────────────┐     JSON-RPC      ┌─────────────────┐
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│                 │ ◄──────────────►  │                 │
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│  MCP Client     │                   │  MCP Server     │
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│  (Claude Code)  │                   │  (PostgreSQL)   │
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│                 │                   │                 │
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└─────────────────┘                   └─────────────────┘
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        │                                      │
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        │  MCP 协议定义了：                      │
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        │  1. 工具发现（list_tools）             │
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        │  2. 工具调用（call_tool）              │
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        │  3. 资源访问（read_resource）           │
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        │  4. 提示模板（get_prompt）              │
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        └──────────────────────────────────────┘

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import { Server } from '@modelcontextprotocol/sdk/server/index.js'
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import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js'
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import { z } from 'zod'
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// 定义 GitHub MCP 服务器
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const server = new Server(
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  { name: 'github-agent', version: '1.0.0' },
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  { capabilities: { tools: {} } }
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)
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// 注册工具：获取 Issue 详情
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server.setRequestHandler('tools/call', async (request) => {
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  const { name, arguments: args } = request.params
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  switch (name) {
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    case 'get_issue': {
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      const { owner, repo, issueNumber } = args as {
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        owner: string, repo: string, issueNumber: number
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      }
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      const res = await fetch(
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        `https://api.github.com/repos/${owner}/${repo}/issues/${issueNumber}`,
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        { headers: { Authorization: `Bearer ${process.env.GITHUB_TOKEN}` } }
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      )
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      const issue = await res.json()
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      return {
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        content: [{
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          type: 'text',
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          text: `## ${issue.title}\n\n**状态**: ${issue.state}\n**标签**: ${issue.labels.map(l => l.name).join(', ')}\n\n${issue.body}`
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        }]
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      }
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    }
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    case 'list_open_prs': {
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      const { owner, repo } = args as { owner: string, repo: string }
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      const res = await fetch(
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        `https://api.github.com/repos/${owner}/${repo}/pulls?state=open`,
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        { headers: { Authorization: `Bearer ${process.env.GITHUB_TOKEN}` } }
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      )
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      const prs = await res.json()
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      const prList = prs.map(pr =>
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        `- [#${pr.number}] ${pr.title} (@${pr.user.login})`
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      ).join('\n')
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      return {
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        content: [{ type: 'text', text: `## 开放的 PR\n\n${prList}` }]
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      }
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    }
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  }
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})
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// 通过标准输入输出连接
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const transport = new StdioServerTransport()
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await server.connect(transport)
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console.error('GitHub MCP Server running on stdio')

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// 使用 MCP Client 连接任意 MCP Server
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import { Client } from '@modelcontextprotocol/sdk/client/index.js'
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import { StdioClientTransport } from '@modelcontextprotocol/sdk/client/stdio.js'
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const transport = new StdioClientTransport({
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  command: 'node',
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  args: ['./db-mcp-server.mjs']
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})
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const client = new Client(
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  { name: 'my-agent', version: '1.0.0' },
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  { capabilities: {} }
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)
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await client.connect(transport)
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// 发现可用工具
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const { tools } = await client.listTools()
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console.log('可用工具:', tools.map(t => t.name))
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// 输出: ['query_database', 'analyze_slow_queries', 'create_index']
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// 调用工具
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const result = await client.callTool({
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  name: 'query_database',
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  arguments: {
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    sql: 'SELECT COUNT(*) FROM users WHERE created_at > NOW() - INTERVAL 7 DAY'
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  }
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})