How It Actually Works
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How It Actually Works
MCP has three parts:
The host — Claude Code (or Claude Desktop) is the host. It manages connections and decides which servers are available.
The server — A small programme that exposes tools. A calendar server exposes tools like get_events, create_event, check_availability. A file search server exposes search_files, read_file. The server is what connects to the actual service.
The protocol — The standard that host and server use to talk to each other. JSON-RPC over stdio. The host asks “what tools do you have?” The server lists them. The host passes a tool call. The server executes it and returns the result.
When you ask Claude to check your calendar, Claude picks the right tool, the server fetches the data, and Claude uses it to answer. The whole exchange happens in milliseconds and you see only the answer.