Model Context Protocol (MCP): connects to external tools and data sources.

A lot of your context lives outside your codebase —MCP bridges that gap 

What Can You Do With It?

Tools give agents 、 the ability to perform actions that help them complete tasks more effectively. 

Adding an MCP Server

claude mcp add

• HTTP servers 
• Stdio servers 

manage MCP servers with /mcp 

Scoping Servers

• Local ：in the current project
• User ： across all your projects.
• Project ：.mcp.json， check into version control so anyone on the codebase

Context Costs

Run /mcp to see what's connected and disable anything you're not actively using.

benefit from using a Skill instead

A Skill has a name and description loaded into context, and Claude only loads the full skill contents when it determines it needs to use it.

If your MCP tools exceed 10% of your context window, Claude Code automatically switches to tool search mode, which discovers the right tools on demand