Ext Apps

MCP Apps

Build interactive UIs for MCP tools — charts, forms, dashboards — that render inline in Claude, ChatGPT and any other compliant chat client.

Why
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Quickstart
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API Docs
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Spec
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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

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: