mcp-development

MCP 开发

带工具的 MCP 服务

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

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

server.tool(
  "search_files",
  "Search for files matching a glob pattern in the project directory",
  {
    pattern: z.string().describe("Glob pattern (e.g., '**/*.ts')"),
    directory: z.string().optional().describe("Base directory to search from"),
  },
  async ({ pattern, directory }) => {
    const files = await glob(pattern, { cwd: directory ?? process.cwd() });
    return {
      content: [
        {
          type: "text",
          text: files.length > 0
            ? files.join("\n")
            : `No files found matching ${pattern}`,
        },
      ],
    };
  }
);

server.tool(
  "run_query",
  "Execute a read-only SQL query against the application database",
  {
    query: z.string().describe("SQL SELECT query to execute"),
    limit: z.number().default(100).describe("Maximum rows to return"),
  },
  async ({ query, limit }) => {
    if (!query.trim().toUpperCase().startsWith("SELECT")) {
      return {
        content: [{ type: "text", text: "Only SELECT queries are allowed" }],
        isError: true,
      };
    }
    const rows = await db.query(`${query} LIMIT ${limit}`);
    return {
      content: [{ type: "text", text: JSON.stringify(rows, null, 2) }],
    };
  }
);

资源

server.resource(
  "schema",
  "db://schema",
  "Current database schema with all tables, columns, and relationships",
  async () => {
    const schema = await db.query(`
      SELECT table_name, column_name, data_type, is_nullable
      FROM information_schema.columns
      WHERE table_schema = 'public'
      ORDER BY table_name, ordinal_position
    `);
    return {
      contents: [
        {
          uri: "db://schema",
          mimeType: "application/json",
          text: JSON.stringify(schema, null, 2),
        },
      ],
    };
  }
);

server.resource(
  "config",
  "config://app",
  "Application configuration (secrets redacted)",
  async () => {
    const config = await loadConfig();
    const safe = redactSecrets(config);
    return {
      contents: [
        {
          uri: "config://app",
          mimeType: "application/json",
          text: JSON.stringify(safe, null, 2),
        },
      ],
    };
  }
);

提示词模板

server.prompt(
  "review-code",
  "Review code changes for bugs, security issues, and style",
  {
    diff: z.string().describe("Git diff or code to review"),
    focus: z.enum(["security", "performance", "style", "all"]).default("all"),
  },
  async ({ diff, focus }) => ({
    messages: [
      {
        role: "user",
        content: {
          type: "text",
          text: `Review this code diff. Focus: ${focus}\n\n${diff}`,
        },
      },
    ],
  })
);

客户端配置

{
  "mcpServers": {
    "project-tools": {
      "command": "node",
      "args": ["./mcp-server/dist/index.js"],
      "env": {
        "DATABASE_URL": "postgres://localhost:5432/app"
      }
    },
    "remote-server": {
      "url": "https://mcp.example.com/sse",
      "headers": {
        "Authorization": "Bearer ${MCP_TOKEN}"
      }
    }
  }
}

传输设置

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

const transport = new StdioServerTransport();
await server.connect(transport);

对于基于 HTTP 的服务，请使用 SSE 传输向客户端流式传输响应。

反模式

• 创建描述含糊、未说明适用场景的工具
• 处理前未使用 Zod schema 验证输入
• 向客户端返回原始错误堆栈跟踪
• 错误响应中缺少 isError: true 标记
• 创建过多粒度过细的工具，而不是可组合的工具
• 未在资源响应中对机密信息进行脱敏

检查清单

• 每个工具都有清晰的描述，说明何时以及为何使用
• 使用 Zod schema 验证输入参数，并提供描述性消息
• 错误响应包含 isError: true 和便于用户理解的消息
• 资源公开只读数据，并对机密信息进行脱敏
• 提示词模板为常见任务提供结构化的起点
• 服务能够在 SIGINT/SIGTERM 时平稳关闭
• 工具可组合（各司其职），而非功能庞杂
• 记录客户端配置及所需的环境变量