Model Context Protocol (MCP) Extensions

The Model Context Protocol provides a flexible core that can be extended with optional modules. These extensions add capabilities such as authentication, UI widgets, experimental features, and domain‑specific logic while keeping the core stable and interoperable.

MCP Extensions Overview

This page explains optional extensions that augment the MCP core. It covers the naming scheme for extensions, official repositories, example extensions for authorization and UI apps, and guidelines for building and publishing your own extensions. Experimental extensions are also described, showing how working groups can prototype ideas before they become formal SEPs.

MCP Apps

MCP Apps let servers return interactive HTML interfaces—charts, forms, dashboards, and more—directly inside an LLM‑driven conversation. They preserve context, enable bi‑directional data flow, leverage host‑side capabilities, and run in a sandboxed iframe for strong security. The page details the architecture, when to use apps, how to scaffold them, and how to test them with Claude or a local host.