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@ -47,13 +47,15 @@
## Build with Agent Skills ## 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](https://agentskills.io/) — install them once, then just ask: The fastest way to build an MCP App is to let your AI coding agent do it. This
repo ships four [Agent Skills](https://agentskills.io/) — install them once,
then just ask:
| Skill | What it does | Try it | | Skill | What it does | Try it |
| --------------------------------------------------------------------------- | ----------------------------------------------------------- | ------------------------------------ | | --------------------------------------------------------------------------- | ----------------------------------------------------------- | ------------------------------------- |
| [`create-mcp-app`](./plugins/mcp-apps/skills/create-mcp-app/SKILL.md) | Scaffolds a new MCP App with an interactive UI from scratch | _"Create an MCP App"_ | | [`create-mcp-app`](./plugins/mcp-apps/skills/create-mcp-app/SKILL.md) | Scaffolds a new MCP App with an interactive UI from scratch | _"Create an MCP App"_ |
| [`migrate-oai-app`](./plugins/mcp-apps/skills/migrate-oai-app/SKILL.md) | Converts an existing OpenAI App to use MCP Apps | _"Migrate from OpenAI Apps SDK"_ | | [`migrate-oai-app`](./plugins/mcp-apps/skills/migrate-oai-app/SKILL.md) | Converts an existing OpenAI App to use MCP Apps | _"Migrate from OpenAI Apps SDK"_ |
| [`add-app-to-server`](./plugins/mcp-apps/skills/add-app-to-server/SKILL.md) | Adds interactive UI to an existing MCP server's tools | _"Add UI to my MCP server"_ | | [`add-app-to-server`](./plugins/mcp-apps/skills/add-app-to-server/SKILL.md) | Adds interactive UI to an existing MCP server's tools | _"Add UI to my MCP server"_ |
| [`convert-web-app`](./plugins/mcp-apps/skills/convert-web-app/SKILL.md) | Turns an existing web app into a hybrid web + MCP App | _"Add MCP App support to my web app"_ | | [`convert-web-app`](./plugins/mcp-apps/skills/convert-web-app/SKILL.md) | Turns an existing web app into a hybrid web + MCP App | _"Add MCP App support to my web app"_ |
### Install the Skills ### Install the Skills
@ -65,9 +67,15 @@ The fastest way to build an MCP App is to let your AI coding agent do it. This r
/plugin install mcp-apps@modelcontextprotocol-ext-apps /plugin install mcp-apps@modelcontextprotocol-ext-apps
``` ```
**Other agents** — any AI coding agent that supports [Agent Skills](https://agentskills.io/) can use these skills. See the [agent skills guide](./docs/agent-skills.md) for manual installation instructions. **Other agents** — any AI coding agent that supports
[Agent Skills](https://agentskills.io/) can use these skills. See the
[agent skills guide](./docs/agent-skills.md) 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. 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 ## Supported Clients
@ -80,23 +88,31 @@ Once installed, verify by asking your agent _"What skills do you have?"_ — you
<a href="https://www.mcpjam.com/"><img src="https://img.shields.io/badge/MCPJam-client-8B5CF6" alt="MCPJam"></a> <a href="https://www.mcpjam.com/"><img src="https://img.shields.io/badge/MCPJam-client-8B5CF6" alt="MCPJam"></a>
</p> </p>
> [!NOTE] > [!NOTE] MCP Apps is an extension to the
> MCP Apps is an extension to the [core MCP specification](https://modelcontextprotocol.io/specification). Host support varies — see the [clients page](https://modelcontextprotocol.io/clients) for the full list. > [core MCP specification](https://modelcontextprotocol.io/specification). Host
> support varies — see the
> [clients page](https://modelcontextprotocol.io/clients) for the full list.
## Why MCP Apps? ## 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, or video player. MCP tools return text and structured data. That works for many cases, but not
when you need an interactive UI, like a chart, form, 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. 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 ## How It Works
MCP Apps extend the Model Context Protocol by letting tools declare UI resources: MCP Apps extend the Model Context Protocol by letting tools declare UI
resources:
1. **Tool definition** — Your tool declares a `ui://` resource containing its HTML interface 1. **Tool definition** — Your tool declares a `ui://` resource containing its
HTML interface
2. **Tool call** — The LLM calls the tool on your server 2. **Tool call** — The LLM calls the tool on your server
3. **Host renders** — The host fetches the resource and displays it in a sandboxed iframe 3. **Host renders** — The host fetches the resource and displays it in a
4. **Bidirectional communication** — The host passes tool data to the UI via notifications, and the UI can call other tools through the host sandboxed iframe
4. **Bidirectional communication** — The host passes tool data to the UI via
notifications, and the UI can call other tools through the host
## Getting Started ## Getting Started
@ -104,11 +120,15 @@ MCP Apps extend the Model Context Protocol by letting tools declare UI resources
npm install -S @modelcontextprotocol/ext-apps npm install -S @modelcontextprotocol/ext-apps
``` ```
**New here?** Start with the [Quickstart Guide](https://modelcontextprotocol.github.io/ext-apps/api/documents/Quickstart.html) to build your first MCP App. **New here?** Start with the
[Quickstart Guide](https://modelcontextprotocol.github.io/ext-apps/api/documents/Quickstart.html)
to build your first MCP App.
## Using the SDK ## Using the SDK
The SDK serves three roles: app developers building interactive Views, host developers embedding those Views, and MCP server authors registering tools with UI metadata. The SDK serves three roles: app developers building interactive Views, host
developers embedding those Views, and MCP server authors registering tools with
UI metadata.
| Package | Purpose | Docs | | Package | Purpose | Docs |
| ------------------------------------------- | --------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------- | | ------------------------------------------- | --------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------- |
@ -117,13 +137,19 @@ The SDK serves three roles: app developers building interactive Views, host deve
| `@modelcontextprotocol/ext-apps/app-bridge` | Embed and communicate with Views in your chat client | [API Docs →](https://modelcontextprotocol.github.io/ext-apps/api/modules/app-bridge.html) | | `@modelcontextprotocol/ext-apps/app-bridge` | Embed and communicate with Views in your chat client | [API Docs →](https://modelcontextprotocol.github.io/ext-apps/api/modules/app-bridge.html) |
| `@modelcontextprotocol/ext-apps/server` | Register tools and resources on your MCP server | [API Docs →](https://modelcontextprotocol.github.io/ext-apps/api/modules/server.html) | | `@modelcontextprotocol/ext-apps/server` | Register tools and resources on your MCP server | [API Docs →](https://modelcontextprotocol.github.io/ext-apps/api/modules/server.html) |
There's no _supported_ host implementation in this repo (beyond the [examples/basic-host](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-host) example). There's no _supported_ host implementation in this repo (beyond the
[examples/basic-host](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-host)
example).
The [MCP-UI](https://github.com/idosal/mcp-ui) client SDK offers a fully-featured MCP Apps framework used by a few hosts. Clients may choose to use it or roll their own implementation. The [MCP-UI](https://github.com/idosal/mcp-ui) client SDK offers a
fully-featured MCP Apps framework used by a few hosts. Clients may choose to use
it or roll their own implementation.
## Examples ## Examples
The [`examples/`](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples) directory contains demo apps showcasing real-world use cases. The
[`examples/`](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples)
directory contains demo apps showcasing real-world use cases.
<!-- prettier-ignore-start --> <!-- prettier-ignore-start -->
| | | | | | | |
@ -150,7 +176,9 @@ The [`examples/`](https://github.com/modelcontextprotocol/ext-apps/tree/main/exa
#### With basic-host #### With basic-host
To run all examples locally using [basic-host](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-host) (the reference host implementation included in this repo): To run all examples locally using
[basic-host](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-host)
(the reference host implementation included in this repo):
```bash ```bash
git clone https://github.com/modelcontextprotocol/ext-apps.git git clone https://github.com/modelcontextprotocol/ext-apps.git
@ -163,7 +191,9 @@ Then open http://localhost:8080/.
#### With MCP Clients #### With MCP Clients
Every Node.js example is published as `@modelcontextprotocol/server-<name>`. To add one to an MCP client that supports stdio (Claude Desktop, VS Code, etc.), use this pattern: Every Node.js example is published as `@modelcontextprotocol/server-<name>`. To
add one to an MCP client that supports stdio (Claude Desktop, VS Code, etc.),
use this pattern:
```json ```json
{ {
@ -176,11 +206,14 @@ Every Node.js example is published as `@modelcontextprotocol/server-<name>`. To
} }
``` ```
For example, to add the map server: `@modelcontextprotocol/server-map`. The Python examples (`qr-server`, `say-server`) use `uv run` instead — see their READMEs for details. For example, to add the map server: `@modelcontextprotocol/server-map`. The
Python examples (`qr-server`, `say-server`) use `uv run` instead — see their
READMEs for details.
#### Local Development #### Local Development
To test local modifications with an MCP client, clone the repo, install, then point your client at a local build: To test local modifications with an MCP client, clone the repo, install, then
point your client at a local build:
```json ```json
{ {
@ -211,9 +244,11 @@ To test local modifications with an MCP client, clone the repo, install, then po
- [Quickstart Guide](https://modelcontextprotocol.github.io/ext-apps/api/documents/Quickstart.html) - [Quickstart Guide](https://modelcontextprotocol.github.io/ext-apps/api/documents/Quickstart.html)
- [API Documentation](https://modelcontextprotocol.github.io/ext-apps/api/) - [API Documentation](https://modelcontextprotocol.github.io/ext-apps/api/)
- [Specification (2026-01-26)](https://github.com/modelcontextprotocol/ext-apps/blob/main/specification/2026-01-26/apps.mdx) ([Draft](https://github.com/modelcontextprotocol/ext-apps/blob/main/specification/draft/apps.mdx)) - [Specification (2026-01-26)](https://github.com/modelcontextprotocol/ext-apps/blob/main/specification/2026-01-26/apps.mdx)
([Draft](https://github.com/modelcontextprotocol/ext-apps/blob/main/specification/draft/apps.mdx))
- [SEP-1865 Discussion](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/1865) - [SEP-1865 Discussion](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/1865)
## Contributing ## Contributing
Contributions are welcome! Please read [CONTRIBUTING.md](CONTRIBUTING.md) for guidelines on how to get started, submit pull requests, and report issues. Contributions are welcome! Please read [CONTRIBUTING.md](CONTRIBUTING.md) for
guidelines on how to get started, submit pull requests, and report issues.