Learn MCP
The Model Context Protocol (MCP) is how an AI application talks to the tools and data it can use. This section explains the moving parts in the order you meet them.
Read in this order
Section titled “Read in this order”- What MCP is, in one diagram: host, client and server, and what each one does.
- Tools, resources and prompts: the three things a server offers, and list caching.
- Transports: stdio and Streamable HTTP: how messages travel, the required headers and what the error codes mean.
- No sessions, no handshake: how 2026-07-28 works: per-request
_meta, multi round-trip requests, subscriptions, and deprecated versus removed.
What this section covers
Section titled “What this section covers”Concepts are written against the 2026-07-28 specification. Where it changed something you may have read elsewhere, such as the removed initialize handshake, the page says so and links to the migration guides.
MCPDev is community documentation. It is not affiliated with the Model Context Protocol project or with the vendors of the clients it covers.