How MCP works: the protocol connecting agents to the world
You’ve probably used MCP from the host side already. This post is the other angle: what is actually on the wire. If the MCP 101 post was the architecture diagram, this one is the packet trace. The short version is that MCP is JSON-RPC 2.0 plus capability discovery, per-request metadata, and two standard transports. As of protocol version 2026-07-28, the core is stateless. If LSP standardized editor-to-language-server traffic, MCP does the same for host-to-tool-server traffic. ...