Chapter 7: MCP Servers

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What is MCP?

MCP (Model Context Protocol) is a standard protocol developed by Anthropic to connect AI models with external data sources and services.

Core Concepts:

• 📡 Unified Interface: Standardized data access
• 🔌 Extensible: Easily add new data sources
• 🔒 Secure: Fine-grained permission control
• ⚡ Efficient: Real-time data access

What can MCP do?

• Connect databases (PostgreSQL, MySQL, MongoDB, etc.)
• Access cloud services (AWS, Google Cloud, Azure)
• Integrate dev tools (GitHub, Jira, Slack)
• Read local filesystem
• Call external APIs

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Configuring MCP Servers

Configuration File Location

7.2 配置 MCP 服务器

~/.config/claude-code/mcp-servers.json

Basic Configuration Structure

{
  "mcpServers": {
    "server-name": {
      "command": "node",
      "args": ["/path/to/server.js"],
      "env": {
        "API_KEY": "your-key"
      }
    }
  }
}

Example: Filesystem Server

7.3 常用 MCP 服务器

{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-filesystem",
        "/home/user/projects"
      ]
    }
  }
}

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Popular MCP Servers

1. Filesystem Server

Install:

npm install -g @modelcontextprotocol/server-filesystem

Configure:

{
  "mcpServers": {
    "filesystem": {
      "command": "mcp-server-filesystem",
      "args": ["/home/user/documents"]
    }
  }
}

Usage:

You: read content of /documents/report.pdf

Claude: [Using MCP filesystem server]
Reading report.pdf...
[Content summary]

2. GitHub Server

Configure:

{
  "mcpServers": {
    "github": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-github"
      ],
      "env": {
        "GITHUB_TOKEN": "ghp_xxxxx"
      }
    }
  }
}

Usage:

You: get my GitHub repository list

Claude: [Using MCP GitHub server]
Found 25 repositories:
1. user/project-a (⭐ 123)
2. user/project-b (⭐ 45)
...

3. PostgreSQL Server

Configure:

{
  "mcpServers": {
    "postgres": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-postgres"
      ],
      "env": {
        "DATABASE_URL": "postgresql://user:pass@localhost/db"
      }
    }
  }
}

Usage:

7.4 自定义 MCP 服务器

You: query total user count in database

Claude: [Using MCP Postgres server]
SELECT COUNT(*) FROM users;
Result: 1,234 users

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Custom MCP Servers

Create Simple MCP Server

// my-mcp-server.js
const { Server } = require('@modelcontextprotocol/sdk/server/index.js');
const { StdioServerTransport } = require('@modelcontextprotocol/sdk/server/stdio.js');

const server = new Server({
  name: 'my-custom-server',
  version: '1.0.0',
}, {
  capabilities: {
    tools: {},
  },
});

// Define tools
server.setRequestHandler('tools/list', async () => {
  return {
    tools: [{
      name: 'get_weather',
      description: 'Get weather for a city',
      inputSchema: {
        type: 'object',
        properties: {
          city: {
            type: 'string',
            description: 'City name',
          },
        },
        required: ['city'],
      },
    }],
  };
});

// Handle tool calls
server.setRequestHandler('tools/call', async (request) => {
  if (request.params.name === 'get_weather') {
    const { city } = request.params.arguments;
    // Implement weather query logic
    return {
      content: [{
        type: 'text',
        text: `Weather in ${city}: Sunny, 25°C`,
      }],
    };
  }
});

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

Configure Custom Server

7.5 MCP 实战案例

{
  "mcpServers": {
    "weather": {
      "command": "node",
      "args": ["/path/to/my-mcp-server.js"]
    }
  }
}

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MCP Practical Examples

Case 1: Database Query Assistant

You: query top 10 products by revenue

Claude: [Using MCP Postgres]
SELECT name, SUM(revenue) as total
FROM products p
JOIN sales s ON p.id = s.product_id
GROUP BY p.id, p.name
ORDER BY total DESC
LIMIT 10;

Top 10 Products:
1. Product A - $125,000
2. Product B - $98,500
...

Case 2: GitHub Automation

You: create a new issue to report login bug

Claude: [Using MCP GitHub]
Creating issue in user/repo...

✓ Issue created: #156
Title: "Bug: Login malfunction"
Labels: bug, priority:high
Assignee: user

Case 3: Documentation Generation

You: generate API docs from database

Claude: [Using MCP Postgres + filesystem]
1. Querying database schema...
2. Analyzing table relationships...
3. Generating documentation...
✓ Created api-docs.md

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Summary

In this chapter, we learned:

• ✅ MCP protocol concept and purpose
• ✅ How to configure MCP servers
• ✅ Popular MCP servers (filesystem, GitHub, database)
• ✅ Create custom MCP servers
• ✅ MCP practical examples

Key Takeaways:

• MCP extends Claude Code's capabilities
• Supports various data sources and services
• Can develop custom MCP servers
• Security configuration is important

Next Step: Chapter 8 introduces the subagent system!

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