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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 bea0ae27f5
 feat: add server helpers, make connect() to default to parent post transport (#165) 
* feat: add server helpers and optional connect() transport

Add `src/server/` with convenience functions for registering MCP App tools
and resources:

- `registerAppTool(server, name, config, handler)`
- `registerAppResource(server, name, uri, config, callback)`

The `transport` parameter in `App.connect()` is now optional, defaulting to
`PostMessageTransport(window.parent)`.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* Update src/server/index.ts

Co-authored-by: Jonathan Hefner <jonathan@hefner.pro>

* fix: refine server helper types

- Make RESOURCE_URI_META_KEY required in McpUiAppToolConfig (tools need a UI resource)
- Make _meta optional in McpUiAppResourceConfig (not all resources need custom metadata)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* refactor: simplify RESOURCE_URI_META_KEY re-export

* refactor: consolidate export statements

---------

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Jonathan Hefner <jonathan@hefner.pro>
2025-12-16 21:25:26 +00:00
.github/workflows fix: Windows compatibility - bun as optional dep, cross-env for examples (#145) 2025-12-16 14:07:38 +00:00
.husky Add pre-commit check for private registry URLs in package-lock.json (#133) 2025-12-16 13:41:50 +00:00
docs fix: add mimeType to resource declarations in examples (#149) 2025-12-15 12:09:47 +00:00
examples feat: add server helpers, make connect() to default to parent post transport (#165) 2025-12-16 21:25:26 +00:00
scripts fix: Windows compatibility - bun as optional dep, cross-env for examples (#145) 2025-12-16 14:07:38 +00:00
specification/draft Fix sandbox-ready notification name in spec to match implementation (#160) 2025-12-16 21:12:16 +00:00
src feat: add server helpers, make connect() to default to parent post transport (#165) 2025-12-16 21:25:26 +00:00
tests/e2e Update e2e screenshots for basic server examples 2025-12-15 11:42:21 -08:00
.gitattributes fix: Windows compatibility - bun as optional dep, cross-env for examples (#145) 2025-12-16 14:07:38 +00:00
.gitignore tests: add Playwright E2E tests with screenshot golden testing (+ fix examples session handling) (#115) 2025-12-13 20:57:27 +00:00
.prettierignore Add basic-server-vanillajs example 2025-12-04 14:28:27 -06:00
.prettierrc.json api: optional Client in AppBridge (allow custom forwarding), better protocol types (AppRequest, AppNotification, AppResult) (#146) 2025-12-13 21:07:13 +00:00
build.bun.ts npm run prettier:fix 2025-11-23 03:15:06 +00:00
CONTRIBUTING.md tests: add Playwright E2E tests with screenshot golden testing (+ fix examples session handling) (#115) 2025-12-13 20:57:27 +00:00
LICENSE add license (#96) 2025-12-08 21:51:19 +01:00
package-lock.json fix: make react a peer dependency to support multiple versions (#163) (#164) 2025-12-16 19:33:05 +00:00
package.json feat: add server helpers, make connect() to default to parent post transport (#165) 2025-12-16 21:25:26 +00:00
playwright.config.ts fix: ensure E2E screenshot tests work consistently across CI and local (#150) 2025-12-15 15:12:36 +00:00
README.md fix: Windows compatibility - bun as optional dep, cross-env for examples (#145) 2025-12-16 14:07:38 +00:00
tsconfig.json Initial commit 2025-11-21 11:56:27 +00:00
typedoc.json Add Quickstart guide for building MCP Apps 2025-12-04 14:28:55 -06:00

README.md

@modelcontextprotocol/ext-apps

npm version API Documentation

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:

The examples/ directory contains additional demo apps showcasing real-world use cases.

To run all examples together:

npm install
npm run examples:start

Then open http://localhost:8080/.

Resources