building-chatgpt-apps

Build ChatGPT Apps with interactive widgets by setting up an MCP server using FastMCP, defining widget resources with HTML delivery, and registering tool responses with widget metadata (_meta containing openai.com/widget). Use the OpenAI Apps SDK to integrate the server and test in Developer Mode.

MCP (Model Context Protocol) is a server framework that exposes resources and tools to ChatGPT. For widget apps, MCP delivers widget HTML and metadata, enabling ChatGPT to render interactive components in conversations and route user interactions back to your app logic.

Yes. Embed HTML widgets by delivering them through an MCP server with proper response metadata (_meta with openai.com/widget). The OpenAI Apps SDK handles registration, and FastMCP simplifies server setup so ChatGPT can render and interact with your widgets.

Start with the OpenAI Apps SDK guide, bootstrap an MCP server using FastMCP, define widget resources and tool metadata, integrate via the SDK, and register your app in Developer Mode for testing. This pattern covers architecture, implementation, and deployment readiness.

FastMCP is the recommended MCP server framework for widget apps because it simplifies resource and tool definition, widget HTML delivery, and response metadata handling. While alternatives exist, FastMCP is optimized for the ChatGPT Apps SDK workflow.

Without widget metadata (_meta with openai.com/widget), ChatGPT cannot identify and render your HTML as an interactive widget; it will display the raw content instead. Proper metadata ensures widgets display correctly and handle user interactions.