UI5 Has Entered the Chat: Building Interactive MCP Apps for SAP

AI can appear in a user interface in several ways. It can add a focused feature such as summarization to a traditional application. It can sit next to the application as a copilot. Or the AI conversation itself can become the main interface. That last case raises an interesting question: if the AI host owns the frame, how can an MCP server provide more than text and JSON? MCP Apps provide an answer. They let an MCP tool return an interactive web interface that a compatible host renders inside the conversation. For our UI5con session, Mike Zaschka and I explored how this model fits SAP user interfaces and built five samples, starting with plain HTML and ending with an ARC-1 transport review. This post focuses on the architecture and lessons from those samples. You can read the final presentation or follow the code in the sample repository. What MCP Apps add to MCP A normal MCP tool already gives a model a structured way to call backend capabilities. For a small result, a text response…