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MCP Apps

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This page is about MCP Apps, the official Model Context Protocol extension (SEP-1865) that lets an MCP server ship an interactive HTML interface, declared as a ui:// resource, which the host renders in a sandboxed iframe inside the conversation. It is not MCP-UI, the community project it grew out of, and it is not the OpenAI Apps SDK. For the core protocol, see Model Context Protocol. For interfaces sent as declarative JSON and drawn with the host's own components, see A2UI.

Overview

MCP Apps is the first official extension to the Model Context Protocol: it lets an MCP tool return an interactive interface, such as a dashboard, form or visualization, that the host renders right in the conversation [10]. The server declares the interface as an HTML resource with a ui:// URI, and a tool links to it through _meta.ui.resourceUri; the host loads it into a sandboxed iframe, and the iframe and host talk MCP-style JSON-RPC over postMessage [3][10]. The design merges the approaches of the community MCP-UI project and the OpenAI Apps SDK into one standard, written by the MCP-UI creators together with MCP maintainers at Anthropic and OpenAI [3][9]. It was proposed as SEP-1865 in November 2025, launched in January 2026 with a stable 2026-01-26 specification, and is developed with its SDK in the modelcontextprotocol/ext-apps repository [9][10][4].

Who uses it

Each server below is a public MCP endpoint named in its operator's own documentation. Each one was checked on 2026-10-28 with no login: an initialize request declaring the io.modelcontextprotocol/ui extension, then tools/list and resources/list. No tools were called. Anthropic's launch partners for interactive connectors could not be checked this way: Figma, Asana, Canva, Amplitude, Hex, monday.com, Box, Slack all answered initialize with HTTP 401 without sign-in [13]. Other open servers, such as Hugging Face, Exa, DeepWiki, listed no ui:// resources.

Who reads it

The MCP documentation lists these hosts: "MCP Apps are currently supported by Claude, Claude Desktop, VS Code GitHub Copilot, Microsoft 365 Copilot, Goose, Postman, MCPJam, and Archestra.AI." [11]. That list does not name ChatGPT, Cursor or Gemini Enterprise, each of which documents support itself [14][21][23].

Recent coverage

See also

References

  1. Ido Salomon, Liad Yosef, Olivier Chafik, Jerome Swannack, Jonathan Hefner, Anton Pidkuiko, Nick Cooper, Bryan Ashley and Alexi Christakis, SEP-1865: MCP Apps - Interactive User Interfaces for MCP - Model Context Protocol (status Final, Extensions Track, created 2025-11-21), checked 2026-10-28: "This SEP has reached Final status and is preserved as a historical record of the design as accepted." "This SEP proposes an extension to MCP (per SEP-1724) that enables servers to deliver interactive user interfaces to hosts." "MCP-UI's adopters, including hosts and providers such as Postman, HuggingFace, Shopify, Goose, and ElevenLabs," "OpenAI's Apps SDK, launched in November 2025, further validated the demand" "The architecture of both the Apps SDK and MCP-UI has significantly informed the design of this specification." — https://modelcontextprotocol.io/seps/1865-mcp-apps-interactive-user-interfaces-for-mcp
  2. idosal (GitHub), SEP-1865: MCP Apps - Interactive User Interfaces for MCP by idosal · Pull Request #1865 · modelcontextprotocol/modelcontextprotocol · GitHub (opened 2025-11-21, merged 2026-01-28), checked 2026-10-28 — https://github.com/modelcontextprotocol/modelcontextprotocol/pull/1865
  3. modelcontextprotocol, MCP Apps specification, specification/2026-01-26/apps.mdx (ext-apps repository), checked 2026-10-28 (text checked at the raw.githubusercontent.com copy): "*Status:* Stable (2026-01-26)" "This extension is identified as: `io.modelcontextprotocol/ui`" "URI MUST start with `ui://` scheme" "`mimeType` MUST be `text/html;profile=mcp-app` (other types reserved for future extensions)" "The flat `_meta["ui/resourceUri"]` format is deprecated. Use `_meta.ui.resourceUri` instead." "The resource content is returned via `resources/read`" "Since UI resources are primarily discovered through tool metadata, Servers MAY omit UI-only resources from `resources/list`" "MCP Apps uses JSON-RPC 2.0 over `postMessage` for iframe-host communication." "Conceptually, UI iframes act as MCP clients, connecting to the host via a `postMessage` transport" "Host MUST send this notification with the complete tool arguments after the View's initialize request completes." "`ui/initialize` → `ui/notifications/initialized` - MCP-like handshake" "This notification is sent at most once and is required before sending `ui/notifications/tool-result`." "If the Host is a web page, it MUST wrap the View and communicate with it through an intermediate Sandbox proxy." "All View content MUST be rendered in sandboxed iframes with restricted permissions." "unifies the approaches pioneered by MCP-UI and the Apps SDK into a single, open standard." — https://github.com/modelcontextprotocol/ext-apps/blob/main/specification/2026-01-26/apps.mdx
  4. modelcontextprotocol, ext-apps README.md (specification table: 2026-01-26 Stable, draft Development), checked 2026-10-28 (text checked at the raw.githubusercontent.com copy): "Build interactive UIs for MCP tools — charts, forms, dashboards — that render inline in Claude, ChatGPT and any other compliant chat client." — https://github.com/modelcontextprotocol/ext-apps
  5. modelcontextprotocol, Release v2.0.4 · modelcontextprotocol/ext-apps · GitHub (published 2026-10-27), checked 2026-10-28: "Patch release: example improvements and a dependency refresh. No changes to the @modelcontextprotocol/ext-apps library API." — https://github.com/modelcontextprotocol/ext-apps/releases/tag/v2.0.4
  6. modelcontextprotocol, Release v2.0.0 · modelcontextprotocol/ext-apps · GitHub (published 2026-09-08), checked 2026-10-28: "ext-apps 2.0 moves to the MCP TypeScript SDK 2.0 split packages. The MCP Apps wire protocol is unchanged: 2.x Views run in 1.x hosts and 2.x hosts render 1.x Views" — https://github.com/modelcontextprotocol/ext-apps/releases/tag/v2.0.0
  7. modelcontextprotocol, Release 1.0.0 · modelcontextprotocol/ext-apps · GitHub (published 2026-01-26), checked 2026-10-28: "stable spec release 2026-01-26 and SDK v1.0.0" — https://github.com/modelcontextprotocol/ext-apps/releases/tag/v1.0.0
  8. npm registry, @modelcontextprotocol/ext-apps package metadata (dist-tag latest 2.0.4; first version 0.0.1 published 2025-12-08), checked 2026-10-28: ""name":"@modelcontextprotocol/ext-apps"" ""latest":"2.0.4"" ""0.0.1":"2025-12-08" — https://registry.npmjs.org/@modelcontextprotocol/ext-apps
  9. Anton Pidkuiko, Olivier Chafik, Ido Salomon, Liad Yosef, Nick Cooper, Sean Strong, Jerome Swannack, Alexi Christakis and Bryan Ashley, MCP Apps: Extending servers with interactive user interfaces | Model Context Protocol Blog, 2025-11-21: "Today we're introducing the proposal for the MCP Apps Extension (SEP-1865) to standardize support for interactive user interfaces in the Model Context Protocol." "The SEP was authored by MCP Core Maintainers at OpenAI and Anthropic, together with the MCP-UI creators and lead maintainers of the MCP UI Community Working Group." "UI templates are resources with the ui:// URI scheme, referenced in tool metadata." — https://blog.modelcontextprotocol.io/posts/2025-11-21-mcp-apps/
  10. MCP Core Maintainers, MCP Apps - Bringing UI Capabilities To MCP Clients | Model Context Protocol Blog, 2026-01-26: "Today, we're announcing that MCP Apps are now live as an official MCP extension." "This is the first official MCP extension, and it's ready for production." "The host fetches the resource, renders it in a sandboxed iframe, and enables bidirectional communication via JSON-RPC over postMessage." "MCP Apps are supported in: Claude - available today both on web and desktop experiences Goose - available today Visual Studio Code - available in Visual Studio Code Insiders ChatGPT - starting this week" "goose, the reference implementation for MCP, supports MCP Apps." "MCP-UI isn't going anywhere." — https://blog.modelcontextprotocol.io/posts/2026-01-26-mcp-apps/
  11. Model Context Protocol, MCP Apps - Model Context Protocol (documentation), checked 2026-10-28: "MCP Apps are currently supported by Claude, Claude Desktop, VS Code GitHub Copilot, Microsoft 365 Copilot, Goose, Postman, MCPJam, and Archestra.AI." — https://modelcontextprotocol.io/extensions/apps/overview
  12. Model Context Protocol, Extensions Overview - Model Context Protocol (documentation), checked 2026-10-28: "To promote an experimental extension to official status, it goes through the standard SEP process (Extensions Track)." — https://modelcontextprotocol.io/extensions/overview
  13. Anthropic, Interactive connectors and MCP Apps | Claude by Anthropic, 2026-01-26: "Starting today, we're bringing interactive connectors to Claude with MCP Apps." "Available in Claude on mobile, web and desktop for Free, Pro, Max, Team, Enterprise plans." — https://claude.com/resources/articles/interactive-tools-in-claude
  14. OpenAI, Add UI to your MCP server – Plugins | OpenAI Developers, checked 2026-10-28: "ChatGPT implements the open MCP Apps standard for UI returned by an MCP server." — https://developers.openai.com/plugins/build/chatgpt-ui
  15. OpenAI, Reference – Plugins | OpenAI Developers, checked 2026-10-28: "Use the MCP Apps specification for shared UI fields and bridge methods. OpenAI extensions are optional and live in window.openai when you want ChatGPT-specific capabilities." — https://developers.openai.com/plugins/reference
  16. OpenAI, Troubleshooting – Plugins | OpenAI Developers, checked 2026-10-28: "Confirm the tool descriptor sets _meta.ui.resourceUri to a registered HTML resource with mimeType: "text/html;profile=mcp-app" (ChatGPT honors _meta["openai/outputTemplate"] as an optional compatibility alias)" — https://developers.openai.com/plugins/deploy/troubleshooting
  17. Harald Kirschner and Connor Peet, Giving Agents a Visual Voice: MCP Apps Support in VS Code (VS Code blog), 2026-01-26: "VS Code is the first major AI code editor with full MCP Apps support. Available now in VS Code Insiders" — https://code.visualstudio.com/blogs/2026/01/26/mcp-apps-support
  18. Microsoft, January 2026 (version 1.109) (VS Code release notes, release date 2026-02-04): "In this release VS Code has added support for MCP Apps. MCP Apps allow servers to display rich, interactive UI in the client." — https://code.visualstudio.com/updates/v1_109
  19. goose, Building MCP Apps | goose | Your open source AI agent, checked 2026-10-28: "MCP Apps let MCP servers return interactive UIs that render directly inside the goose chat interface, rather than responding with text alone." "MCP Apps support in goose is experimental and based on a draft specification." — https://goose-docs.ai/docs/tutorials/building-mcp-apps/
  20. Microsoft, MCP apps in Microsoft 365 Copilot - Build interactive UI widgets | Microsoft Learn (last updated 2026-09-30): "MCP apps are interactive UI widgets that run inside Microsoft 365 Copilot, powered by Model Context Protocol (MCP) servers." "Microsoft 365 Copilot supports both, though not all capabilities are available." — https://learn.microsoft.com/en-us/microsoft-365/copilot/extensibility/plugin-mcp-apps
  21. Cursor, MCP Apps and Team Marketplaces for Plugins · Cursor (changelog 2.6), 2026-03-03: "MCP Apps support interactive user interfaces like charts from Amplitude, diagrams from Figma, and whiteboards from tldraw directly inside Cursor." — https://cursor.com/changelog/2-6
  22. Postman, Interact with MCP servers (Postman Docs), checked 2026-10-28 (text checked at the page's Markdown copy, interact.md): "Servers that support the [MCP Apps Extension](https://github.com/modelcontextprotocol/ext-apps) can also return interactive user interfaces." — https://learning.postman.com/docs/use/send-requests/protocols/mcp-requests/interact/
  23. Dave Wang, Devs guide to MCP Apps in Gemini | Google Cloud Blog, 2026-10-20: "This open Model Context Protocol (MCP) extension pairs a tool with a live UI. In Gemini Enterprise, that UI renders directly in the chat flow inside a sandboxed iframe" — https://cloud.google.com/blog/topics/developers-practitioners/devs-guide-to-mcp-apps-in-gemini
  24. MCP-UI, About | MCP-UI, checked 2026-10-28: "Today, mcp-ui implements the MCP Apps standard" — https://mcpui.dev/about
  25. Google A2UI Team, Ido Salomon and Liad Yosef, A2UI + MCP Apps: Combining the best of declarative and custom agentic UIs - Google Developers Blog, 2026-06-17: "Model Context Protocol (MCP) Apps offer creative freedom within an iframe using standard web technologies." "Instead of sending raw HTML, CSS, and JavaScript, A2UI employs a JSON payload to define what to render, allowing the host application to handle the presentation through its native components." — https://developers.googleblog.com/a2ui-and-mcp-apps/
  26. Excalidraw, excalidraw-mcp README.md, checked 2026-10-28 (text checked at the raw.githubusercontent.com copy): "Works with any client that supports [MCP Apps](https://modelcontextprotocol.io/docs/extensions/apps) — Claude, ChatGPT, VS Code, Goose, and others." — https://github.com/excalidraw/excalidraw-mcp
  27. Metabind, Try Metabind in Claude or ChatGPT - Metabind, checked 2026-10-28: "The Metabind connector is a public MCP server with the Metabind Component Kit built in" — https://docs.metabind.ai/guides/getting-started/try-metabind
  28. Coronet, Connect Coronet Arcade to ChatGPT, Claude & Cursor | MCP, checked 2026-10-28: "Playable boards require MCP Apps support." — https://coronet.one/connect/
  29. Richard MacManus, The New Stack, Agent UI Standards Multiply: MCP Apps and Google's A2UI - The New Stack, 2025-12-19: "It's also noteworthy that OpenAI is a contributor to the MCP Apps project, which derives from both the MCP-UI project (created by Ido Salomon and Liad Yosef, who both now work for Monday.com) and OpenAI's Apps SDK." — https://thenewstack.io/agent-ui-standards-multiply-mcp-apps-and-googles-a2ui/
  30. Thomas Claburn, The Register, Claude supports MCP Apps, presents UI within chat window, 2026-01-26: "The MCP Apps Extension (SEP-1865) was first proposed back in November 2025 and is based on MCP-UI and the OpenAI Apps SDK." — https://www.theregister.com/special-features/2026/01/26/claude-supports-mcp-apps-presents-ui-within-chat-window/4645652
  31. Russell Brandom, TechCrunch, Anthropic launches interactive Claude apps, including Slack and other workplace tools | TechCrunch, 2026-01-26: "The system is similar to OpenAI's Apps system, which launched in October and enables interactive third-party tools." — https://techcrunch.com/2026/01/26/anthropic-launches-interactive-claude-apps-including-slack-and-other-workplace-tools/

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