Section 2

MCP Primitives

A protocol is only as useful as what it lets you build. This section takes MCP from "a standard for connecting hosts and servers" (Section 1) to the three concrete things a server can actually expose — Tools, Resources, and Prompts — plus the transport layer that carries every message any of them ever send. Every chapter in this section proves the same underlying claim with a runnable example: a server-declared contract is only real if something checks caller-supplied input against it, names the specific reason for every failure, and does so reliably regardless of how the input physically arrives.