Complete MCP guide | The Claude Codex

What is an MCP?

The Model Context Protocol (MCP) is an open protocol created by Anthropic that lets Claude Code connect to external services. It's the universal adapter between Claude Code and the rest of the digital world.

How to install an MCP

Installation takes three steps:

1. Use the dedicated command

claude mcp add filesystem -- npx -y @modelcontextprotocol/server-filesystem /home/your-user/projects

2. Configure in settings.json

{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-filesystem",
        "/path/to/your/folder"
      ]
    }
  }
}

3. Verify the connection

claude mcp list

# Expected output:
# filesystem: connected
#   Tools: read_file, write_file, list_directory, search_files, ...

Essential MCPs

MCP	Level	Use case
Filesystem	Beginner	Read, write, and explore files
GitHub	Intermediate	Manage PRs, issues, and CI/CD workflows
PostgreSQL / SQLite	Intermediate	Query your databases
Puppeteer / Playwright	Advanced	Automate a web browser
Slack	Beginner	Read and send messages
Gmail	Beginner	Manage your emails

Best practices

Principle of least privilege: grant each MCP only the necessary permissions
Per-project configuration: use .claude/settings.json at the root of each project
Combine MCPs: the real power emerges when Claude chains multiple MCPs together
Document your configurations: add a CLAUDE.md file to explain which MCPs are in use

Next steps

Now that you've mastered MCPs, explore Skills to teach new behaviors to Claude Code, or refine your prompting for optimal results.