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
- TypeScript 76.4%
- MDX 19.3%
- JavaScript 4.3%
| Filename | Latest commit message | Latest commit date |
|---|---|---|
9f09932baf* build app-with-deps
* make registerAppTool more interchangeable w/ server.registerTool
* feat: use structuredContent in all example servers
All servers now return structuredContent alongside JSON text content.
All mcp-apps now read structuredContent directly (no JSON.parse fallback).
Updated servers:
- basic-server-vanillajs
- budget-allocator-server
- cohort-heatmap-server
- customer-segmentation-server
- integration-server
- scenario-modeler-server
- system-monitor-server
- threejs-server
- video-resource-server
- wiki-explorer-server
* feat: add outputSchema to all example servers
Define output schemas for structuredContent validation:
- basic-server-vanillajs: { time: string }
- budget-allocator-server: BudgetDataResponseSchema
- cohort-heatmap-server: CohortDataSchema
- customer-segmentation-server: customers/segments schema
- integration-server: { time: string }
- scenario-modeler-server: templates/defaultInputs schema
- system-monitor-server: SystemStatsSchema
- threejs-server: { code, height }
- video-resource-server: { videoUri, description }
- wiki-explorer-server: { page, links, error }
* prettier:fix
* make registerAppTool more interchangeable w/ server.registerTool
* feat: use structuredContent in all example servers
All servers now return structuredContent alongside JSON text content.
All mcp-apps now read structuredContent directly (no JSON.parse fallback).
Updated servers:
- basic-server-vanillajs
- budget-allocator-server
- cohort-heatmap-server
- customer-segmentation-server
- integration-server
- scenario-modeler-server
- system-monitor-server
- threejs-server
- video-resource-server
- wiki-explorer-server
* feat: add outputSchema to all example servers
Define output schemas for structuredContent validation:
- basic-server-vanillajs: { time: string }
- budget-allocator-server: BudgetDataResponseSchema
- cohort-heatmap-server: CohortDataSchema
- customer-segmentation-server: customers/segments schema
- integration-server: { time: string }
- scenario-modeler-server: templates/defaultInputs schema
- system-monitor-server: SystemStatsSchema
- threejs-server: { code, height }
- video-resource-server: { videoUri, description }
- wiki-explorer-server: { page, links, error }
* prettier:fix
* revert: remove unrelated workflow, version, and arch changes
* chore: update package-lock.json
* refactor(basic-server-vanillajs): address PR review comments
- Simplify server.ts to return plain time string in text content (not JSON),
matching the quickstart guide pattern
- Add defensive coding in mcp-app.ts with optional chaining and fallback
to handle potential type mismatches gracefully
* refactor: restore rich text formatting for LLM-readable content
Restore the human-readable text formatting functions that were removed,
providing meaningful summaries in the text content while keeping
structuredContent for programmatic UI consumption:
- budget-allocator-server: formatBudgetSummary with config overview
- cohort-heatmap-server: formatCohortSummary with retention stats
- scenario-modeler-server: formatScenarioSummary with financial metrics
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| .github/workflows | ||
| .husky | ||
| docs | ||
| examples | ||
| scripts | ||
| specification/draft | ||
| src | ||
| tests/e2e | ||
| .gitattributes | ||
| .gitignore | ||
| .prettierignore | ||
| .prettierrc.json | ||
| build.bun.ts | ||
| CONTRIBUTING.md | ||
| LICENSE | ||
| package-lock.json | ||
| package.json | ||
| playwright.config.ts | ||
| README.md | ||
| RELEASES.md | ||
| tsconfig.json | ||
| typedoc.json | ||
@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
npm install -S @modelcontextprotocol/ext-apps
Or edit your package.json manually:
{
"dependencies": {
"@modelcontextprotocol/ext-apps": "^0.0.1"
}
}
Examples
Start with these foundational examples to learn the SDK:
examples/basic-server-vanillajs— MCP server + MCP App using vanilla JSexamples/basic-server-react— MCP server + MCP App using Reactexamples/basic-server-vue— MCP server + MCP App using Vueexamples/basic-server-svelte— MCP server + MCP App using Svelteexamples/basic-server-preact— MCP server + MCP App using Preactexamples/basic-server-solid— MCP server + MCP App using Solidexamples/basic-host— MCP host application supporting MCP Apps
The examples/ directory contains additional demo apps showcasing real-world use cases.
To run all examples together:
npm install
npm start
Then open http://localhost:8080/.