MCP Server Integration Intermediate

The Model Context Protocol (MCP) lets Claude Code connect to external tools and services. MCP servers run as separate processes and provide Claude with additional capabilities like database access, web search, and API integrations.

What is MCP?

MCP (Model Context Protocol) is an open standard that lets AI models interact with external tools through a standardized interface. An MCP server:

Runs as a separate process (local or remote)
Exposes tools that Claude can invoke
Handles communication via JSON-RPC over stdio or HTTP
Provides resources (data) and prompts alongside tools

Configuration

MCP servers can be configured at two levels:

Project-level (.mcp.json)

.mcp.json (Project Root)

{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-filesystem", "/path/to/allowed/dir"]
    },
    "github": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-github"],
      "env": {
        "GITHUB_TOKEN": "ghp_your_token_here"
      }
    }
  }
}

User-level (claude_desktop_config.json)

~/.claude/claude_desktop_config.json

{
  "mcpServers": {
    "web-search": {
      "command": "npx",
      "args": ["-y", "@anthropic/mcp-server-web-search"],
      "env": {
        "BRAVE_API_KEY": "your_key_here"
      }
    }
  }
}

Popular MCP Servers

Server	Package	Provides
Filesystem	`@modelcontextprotocol/server-filesystem`	File read/write/search beyond working directory
GitHub	`@modelcontextprotocol/server-github`	Issues, PRs, repos, actions
PostgreSQL	`@modelcontextprotocol/server-postgres`	Database queries and schema exploration
Slack	`@modelcontextprotocol/server-slack`	Read/send messages, channels, users
Web Search	`@anthropic/mcp-server-web-search`	Search the web via Brave Search API
Memory	`@modelcontextprotocol/server-memory`	Persistent knowledge graph storage

Multi-Server Setup

You can run multiple MCP servers simultaneously. Claude will have access to tools from all configured servers:

.mcp.json

{
  "mcpServers": {
    "github": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-github"],
      "env": { "GITHUB_TOKEN": "$GITHUB_TOKEN" }
    },
    "postgres": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-postgres"],
      "env": { "DATABASE_URL": "postgresql://user:pass@localhost:5432/mydb" }
    },
    "slack": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-slack"],
      "env": { "SLACK_BOT_TOKEN": "$SLACK_TOKEN" }
    }
  }
}

Security: Never commit API keys or tokens to git. Use environment variable references ($GITHUB_TOKEN) and set them in your shell profile, or use a .env file excluded from git.

Debugging MCP Connections

Terminal

# Check if Claude Code recognizes your MCP servers
Claude > /doctor

# Test an MCP server manually
$ npx -y @modelcontextprotocol/server-github --help

# Check for errors in Claude Code logs
$ cat ~/.claude/logs/mcp.log

Common Issues:

Server not found: Ensure the npx package name is correct and Node.js is installed
Auth failures: Check that environment variables are set correctly
Timeout: Some servers take a few seconds to start. Restart Claude Code if tools are not showing up
Permission denied: Claude Code needs permission to use MCP tools. Check your permission settings

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