A technical overview of the protocol, current to the 2026-07-28 specification.
The MCP overview explains how MCP works: the roles, the wire format, what a server exposes, how servers ask for input, the transports, authorization, and what changed when the protocol went stateless in revision 2026-07-28. It is written for engineers who want a working model of the protocol before reading the specification.
Building a server? @cyanheads/mcp-ts-core is an agent-native TypeScript framework for building MCP servers on the current spec. Every scaffold ships Agent Skills that your coding agent follows to design, test, and release the server, and the server answers legacy and modern clients alike. Scaffold a project with:
bunx @cyanheads/mcp-ts-core init my-mcp-serverLooking for working servers? The servers I maintain are listed on my GitHub profile. The Fleet Map lists every hosted one with its tools, endpoint, and install snippets.
| Guide | Covers |
|---|---|
| MCP overview | Hosts, clients, and servers; messages and statelessness; tools, resources, and prompts; multi round-trip requests; notifications and caching; stdio and Streamable HTTP; authorization; extensions; security |
| Legacy vs. modern servers | Revision history from 2024-11-05, what changed in 2026-07-28, deprecations, era compatibility and detection, and a migration checklist for server authors |
These skills ship with mcp-ts-core and are written for coding agents. They reference the framework's APIs, but the practices carry over to any SDK. Hand one to your agent and ask it to distill the guidance for your stack.
| Looking to… | Skill |
|---|---|
| Design an MCP server: tool surface, resources, and service layer for a domain or API | design-mcp-server |
| Build a good tool: naming, schemas, response design, errors | add-tool |
| Audit how your tool descriptions and schemas read to a model | tool-defs-analysis |
| Shape large or awkward responses: overflow handling, payload shaping, retrieval patterns | techniques |
| Test a server against live inputs, including adversarial ones | field-test |
| Review a server for security gaps: prompt injection, input sinks, auth, leakage | security-pass |
| Resource | Link |
|---|---|
Specification (2026-07-28) |
modelcontextprotocol.io/specification/2026-07-28 |
| Changelog for this revision | Key changes |
| Deprecated features registry | Deprecated |
| Schema (source of truth) | schema.ts |
| Extensions | Extensions overview |
| Enhancement proposals | SEPs |
| Server registry | MCP Registry |
| Debugging | MCP Inspector |
Official SDKs: TypeScript · Python · Go · Java · Kotlin · C# · Rust · Swift · Ruby · PHP