MCP Apps
MCP Apps let a tool return an interactive interface, such as a chart, a form or a map, that the AI app renders right in the conversation. These guides explain how the extension works, how to build one, and what behaves differently between AI apps.
Start with what MCP Apps are.
What are MCP Apps
MCP Apps let a tool show an interactive UI in the chat. Learn how the ui:// resource, the sandboxed view and the host bridge fit together.
Build an MCP App
Build an MCP App in TypeScript with the official ext-apps package, test its tools and view with MCP Inspector, and connect it to an AI app.
MCP Apps vs Apps SDK
MCP Apps and the OpenAI Apps SDK share one server model and one UI bridge. Here is what's shared, what's ChatGPT-only and how to target both.
Host compatibility
Which AI apps show MCP Apps interfaces today, how they differ on Claude, ChatGPT, VS Code and Cursor, and how to check a host yourself.
App data flow
Follow a tool result from the server to an MCP App view, see how the view calls tools, and learn how it updates what the model knows.
Test and debug apps
Test an MCP App with the MCP Inspector, basic-host and Claude Desktop, then fix a blank view, a blocked request, a missing resource or a wrong MIME type.