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Mirror of https://github.com/modelcontextprotocol/ext-apps — Official repo for spec & SDK of MCP Apps protocol - standard for UIs embedded AI chatbots, served by MCP servers

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Olivier Chafik f6ebefe238 Add server selector to basic-host example (#95 ) * Add server selector to basic-host example - Add ServerSelector component to switch between MCP servers - Run all example servers concurrently on ports 3101-3107 - Update examples:start to launch all servers with assigned ports 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com> * Move server selector into tool call panel - Server selector now in same component as tool selector - Tool call results persist across server switches - Connection caching avoids reconnects when switching servers - Display server name with tool name in results (ServerName:ToolName) 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com> --------- Co-authored-by: Claude <noreply@anthropic.com>		2025-12-08 18:45:50 +01:00
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package.json	Add server selector to basic-host example (#95 )	2025-12-08 18:45:50 +01:00
README.md	Add Quickstart guide for building MCP Apps	2025-12-04 14:28:55 -06:00
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README.md

@modelcontextprotocol/ext-apps

This repo contains the SDK and specification for MCP Apps Extension (SEP-1865).

MCP Apps are a proposed standard inspired by MCP-UI and OpenAI's Apps SDK to allow MCP Servers to display interactive UI elements in conversational MCP clients / chatbots.

Overview

This SDK serves two audiences:

App Developers

Build interactive UIs that run inside MCP-enabled chat clients.

SDK for Apps: @modelcontextprotocol/ext-apps — API Docs
React hooks: @modelcontextprotocol/ext-apps/react — API Docs

Host Developers

Embed and communicate with MCP Apps in your chat application.

SDK for Hosts: @modelcontextprotocol/ext-apps/app-bridge — API Docs

There's no supported host implementation in this repo (beyond the examples/basic-host example).

We have contributed a tentative implementation of hosting / iframing / sandboxing logic to the MCP-UI repository, and expect OSS clients may use it, while other clients might roll their own hosting logic.

Installation

This repo is in flux and isn't published to npm yet. When it is, it will use the @modelcontextprotocol/ext-apps package.

In the meantime you can depend on the SDK library in a Node.js project by installing it with its git URL:

npm install -S git+https://github.com/modelcontextprotocol/ext-apps.git

Your package.json will then look like:

{
  "dependencies": {
    "@modelcontextprotocol/ext-apps": "git+https://github.com/modelcontextprotocol/ext-apps.git"
  }
}

Note

The build tools (esbuild, tsx, typescript) are in dependencies rather than devDependencies. This is intentional: it allows the prepare script to run when the package is installed from git, since npm doesn't install devDependencies for git dependencies.

Once the package is published to npm with pre-built dist/, these can be moved back to devDependencies.

Examples

examples/basic-server-react — Example MCP server with tools that return UI Apps (React)
examples/basic-server-vanillajs — Example MCP server with tools that return UI Apps (vanilla JS)
examples/basic-host — Bare-bones example of hosting MCP Apps

To run the examples end-to-end:

npm i
npm run examples:start

Then open http://localhost:8080/