MCP Extensions for Claude Code: Connect GitHub, Databases, and APIs

What MCP Extensions Are

MCP (Model Context Protocol) is the same protocol Claude Code uses internally to call tools. MCP servers extend that interface to external services — GitHub, PostgreSQL, Slack, and anything else with an MCP implementation. Once configured, these tools appear to Claude Code as native capabilities.

Official MCP Servers

Install official servers via npm:

npm install -g @anthropic-ai/mcp-server-github
npm install -g @anthropic-ai/mcp-server-filesystem

Add to .mcp.json in your project root:

{
  "mcpServers": {
    "github": {
      "command": "npx",
      "args": ["@anthropic-ai/mcp-server-github"],
      "env": { "GITHUB_TOKEN": "your-token-here" }
    }
  }
}

Restart your Claude Code session. The new tools appear in the tools list.

Third-Party MCP Servers

The MCP ecosystem includes community servers for PostgreSQL, MySQL, Slack, AWS, GCP, GitLab, and more. Use the same .mcp.json configuration regardless of whether the server is official or community-built.

Debugging MCP Connections

If an MCP server is not appearing, run claude --debug to see discovery logs. Check that the server binary is in your PATH, required env vars are set, and the transport type (stdio by default) is supported.