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 |
|---|---|---|
37aab03de0* docs: add tool visibility and restructure _meta.ui - Restructure tool metadata: `_meta["ui/resourceUri"]` → `_meta.ui.resourceUri` - Add `visibility` array field: ["model"], ["apps"], or ["model", "apps"] - Default ["model"] preserves standard MCP behavior - ["apps"] enables widget-only tools hidden from agent - Add McpUiToolMeta interface for type safety - Add Design Decision #4 explaining approach vs OpenAI's two-field model 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com> * address PR review comments - Change default visibility to ["model", "apps"] - Add deprecation notice for flat ui/resourceUri format - Add McpUiToolMeta and McpUiToolVisibility to spec.types.ts - Improve tools/list and tools/call behavior wording 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com> * chore: regenerate schemas for McpUiToolMeta types 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com> * feat: tool visibility and nested _meta.ui format - Rename visibility "apps" → "app" in McpUiToolVisibility type - Add _meta.ui.resourceUri nested format (deprecate flat format) - Add getToolUiResourceUri() utility with backward compatibility - Add visibility demo to system-monitor-server: - get-system-stats: visibility ["model"] with resourceUri - refresh-stats: visibility ["app"] (app-only polling) - Update all example servers to use new _meta.ui format - Add 11 unit tests for getToolUiResourceUri() 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com> * chore: regenerate schemas with updated dependencies * feat: export McpUiToolMeta type and add type annotations - Export McpUiToolMeta and McpUiToolVisibility types from types.ts - Export corresponding Zod schemas (McpUiToolMetaSchema, McpUiToolVisibilitySchema) - Add `as McpUiToolMeta` type annotations to all example servers - Update docs/quickstart.md with proper typing Ensures type safety for `_meta.ui` tool metadata across the codebase. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com> * 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> * feat: update McpUiAppToolConfig to support both _meta.ui and flat formats * refactor: simplify server helper imports * docs: add deprecation notice and improve resourceUri documentation * feat: add backward compat normalization in registerAppTool - If _meta.ui.resourceUri is set, also set legacy flat key - If legacy flat key is set, also set _meta.ui.resourceUri - Preserves existing visibility when merging - Does not overwrite if both formats already set * refactor: avoid mutating config arg in registerAppTool * style: format with prettier --------- Co-authored-by: Claude <noreply@anthropic.com> Co-authored-by: Olivier Chafik <ochafik@anthropic.com> Co-authored-by: Jonathan Hefner <jonathan@hefner.pro> |
||
| .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 | ||
| 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— Example MCP server with tools that return UI Apps (vanilla JS)examples/basic-server-react— Example MCP server with tools that return UI Apps (React)examples/basic-host— Bare-bones example of hosting MCP Apps
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/.