MCP Architecture

Hosts, clients, servers, and transports — how the MCP protocol layers fit together.

What You Will Learn

• Hosts: the applications that embed Claude (Claude Code, Claude Desktop)
• MCP clients: the connection manager inside the host
• MCP servers: processes that expose tools and resources
• Transports: stdio (local process) vs SSE (remote HTTP)
• The request/response lifecycle: how a tool call flows through MCP