MCP in 2026: where the ecosystem actually is

MCP went from "spec on GitHub" to "thing every Claude client speaks" in roughly 18 months. Here's the lay of the land as of May 2026.

Stable

• stdio transport is the default for local servers and the on-ramp for new builders.
• HTTPS + OAuth is the default for remote servers; auth flows have settled.
• Tools, resources, and prompts are all production-shaped. The schemas have stopped moving.
• Reference servers for the common SaaS apps (GitHub, Linear, Slack, Notion, Stripe) are mature.

Emerging

• MCP marketplaces. A few open registries are starting to host community servers with verified-publisher badges.
• Per-tool consent UIs in clients (Claude Code already, others coming) so users can approve a single tool without opening the whole server.
• Streaming tool responses for long-running operations. Useful for query-heavy tools.

Still rough

• Cross-server composition. Wiring server A's output into server B's input is mostly user-driven; no clean primitives yet.
• Server-to-server discovery. Nothing standard.
• Sandboxing. A wide-open implementation problem.

For exam purposes: know the three primitives, know the two transports, know that tools are for verbs and resources for nouns. That's the testable surface.