MCP Apps MCP Apps GitHub Specification Preparing search index... MCP Apps Build interactive UIs for MCP tools — charts, forms, dashboards — that render inline in Claude, ChatGPT and any other compliant chat client. Why · Quickstart · API Docs · Spec · Contributing Excalidraw built with MCP Apps, running in Claude Table of Contents * Build with Agent Skills * Supported Clients * Why MCP Apps? * How It Works * Getting Started * Using the SDK * Examples * Specification * Resources * Contributing Build with Agent Skills The fastest way to build an MCP App is to let your AI coding agent do it. This repo ships four Agent Skills — install them once, then just ask: Skill What it does Try it create-mcp-app Scaffolds a new MCP App with an interactive UI from scratch "Create an MCP App" migrate-oai-app Converts an existing OpenAI App to use MCP Apps "Migrate from OpenAI Apps SDK" add-app-to-server Adds interactive UI to an existing MCP server's tools "Add UI to my MCP server" convert-web-app Turns an existing web app into a hybrid web + MCP App "Add MCP App support to my web app" Install the Skills Claude Code — install via the plugin marketplace: / plugin marketplace add modelcontextprotocol / ext - apps / plugin install mcp - apps @ modelcontextprotocol - ext - apps Copy Other agents — any AI coding agent that supports Agent Skills can use these skills. See the agent skills guide for manual installation instructions. Once installed, verify by asking your agent "What skills do you have?" — you should see create-mcp-app , migrate-oai-app , add-app-to-server , and convert-web-app in the list. Then just ask it to create or migrate an app and it will guide you through the rest. Supported Clients Note MCP Apps is an extension to the core MCP specification . Host support varies — see the clients page for the full list. Why MCP Apps? MCP tools return text and structured data. That works for many cases, but not when you need an interactive UI, like a chart, form, design canvas or video player. MCP Apps provide a standardized way to deliver interactive UIs from MCP servers. Your UI renders inline in the conversation, in context, in any compliant host. How It Works MCP Apps extend the Model Context Protocol by letting tools declare UI resources: * Tool definition — Your tool declares a ui:// resource containing its HTML interface * Tool call — The LLM calls the tool on your server * Host renders — The host fetches the resource and displays it in a sandboxed iframe * Bidirectional communication — The host passes tool data to the UI via notifications, and the UI can call other tools through the host Getting Started Requires Node.js 20+. The base MCP SDK packages are ^2.0.0 peers of ext-apps ( @modelcontextprotocol/core is a required peer that client already depends on, so npm installs it for you). For a View or host: npm install -S @modelcontextprotocol/ext-apps \ @modelcontextprotocol/client@^2.0.0 \ zod@^4.2.0 Copy For an MCP server, add the server package (and, for HTTP transports, the Node and Express adapters): npm install -S @modelcontextprotocol/ext-apps \ @modelcontextprotocol/client@^2.0.0 \ @modelcontextprotocol/server@^2.0.0 \ @modelcontextprotocol/node@^2.0.0 \ @modelcontextprotocol/express@^2.0.0 \ zod@^4.2.0 Copy The wire protocol is unchanged between ext-apps 1.x and 2.x: a 2.x View works in a 1.x host and a 2.x host renders 1.x Views. See the migration guide when upgrading from 1.x. New here? Start with the Quickstart Guide to build your first MCP App. Using the SDK The SDK serves three roles: app developers building interactive Views, host developers embedding those Views, and MCP server authors registering tools with UI metadata. Package Purpose Docs @modelcontextprotocol/ext-apps Build interactive Views (App class, PostMessageTransport) API Docs → @modelcontextprotocol/ext-apps/react React hooks for Views (useApp, useHostStyles, etc.) API Docs → @modelcontextprotocol/ext-apps/app-bridge Embed and communicate with Views in your chat client API Docs → @modelcontextprotocol/ext-apps/server Register tools and resources on your MCP server API Docs → There's no supported host implementation in this repo (beyond the examples/basic-host example). The MCP-UI client SDK offers a fully-featured MCP Apps framework used by a few hosts. Clients may choose to use it or roll their own implementation. Examples The examples/ directory contains demo apps showcasing real-world use cases. Map Three.js ShaderToy Sheet Music Wiki Explorer Cohort Heatmap Scenario Modeler Budget Allocator Customer Segmentation System Monitor Transcript Video Resource PDF Server QR Code (Python) Say Demo Starter Templates The same app built with different frameworks — pick your favorite! React · Vue · Svelte · Preact · Solid · Vanilla JS Running the Examples With basic-host To run all examples locally using basic-host (the reference host implementation included in this repo): git clone https://github.com/modelcontextprotocol/ext-apps.git cd ext-apps npm install npm start Copy Then open http://localhost:8080/ . With MCP Clients Every Node.js example is published as @modelcontextprotocol/server-<name> . To add one to an MCP client that supports stdio (Claude Desktop, VS Code, etc.), use this pattern: { "mcpServers" : { "<name>" : { "command" : "npx" , "args" : [ "-y" , "@modelcontextprotocol/server-<name>" , "--stdio" ] } } } Copy For example, to add the map server: @modelcontextprotocol/server-map . The Python examples ( qr-server , say-server ) use uv run instead — see their READMEs for details. Local Development To test local modifications with an MCP client, clone the repo, install, then point your client at a local build: { "mcpServers" : { "<name>" : { "command" : "bash" , "args" : [ "-c" , "cd ~/code/ext-apps/examples/<name>-server && npm run build >&2 && node dist/index.js --stdio" ] } } } Copy Specification Version Status Link 2026-01-26 Stable specification/2026-01-26/apps.mdx draft Development specification/draft/apps.mdx Resources * Quickstart Guide * API Documentation * Specification (2026-01-26) ( Draft ) * SEP-1865 Discussion Contributing Contributions are welcome! Please read CONTRIBUTING.md for guidelines on how to get started, submit pull requests, and report issues. Settings Member Visibility * Protected * Inherited * External Theme OS Light Dark On This Page Table of Contents Build with Agent Skills * Install the Skills Supported Clients Why MCP Apps? How It Works Getting Started Using the SDK Examples * Starter Templates * Running the Examples * * With basic- host * With MCP Clients * Local Development Specification Resources Contributing GitHub Specification MCP Apps * Loading... Generated using TypeDoc with typedoc-github-theme