Already 9 months old when the scout caught it.
MCP Apps
What it is
MCP Apps is an official extension to the Model Context Protocol that lets an MCP server ship an interactive user interface — a form, chart, dashboard, or multi-step widget — alongside its tools. The server declares a UI resource, the host renders it in a sandboxed iframe, and the two sides exchange messages so the UI can call tools and show live results, instead of the model just describing things in text.
Why it's emerging now
MCP standardized how agents call tools and read data, but tool results were still limited to text and simple structured blocks even when the underlying action — booking a flight, editing a spreadsheet, picking from a map — is naturally visual or interactive. MCP Apps closes that gap. It was proposed in late 2025 and became the first official MCP extension on January 26, 2026 under the protocol's new Extensions framework (itself finalized in the July 2026 spec release); by August it's supported across Claude, ChatGPT, VS Code's GitHub Copilot, Microsoft 365 Copilot, and several other MCP hosts, which is what pushed it from "extension proposal" to something worth knowing.
How it relates to what you know
It's a direct extension of MCP, already on your ledger — same servers, same tool-calling model, plus a defined way to return a rendered UI instead of only text or JSON. It's the MCP ecosystem's answer to the same problem computer use (GUI agents) approaches from the other direction: rather than the agent operating a generic screen, the server hands the host a purpose-built interface for its own tools.