The web front end (chat UI) that the business actually interacts with often needs to be adapted to the domain. We have tried to use the various chat UIs out of the box with customization on top and all of this has failed spectacularly. There are cases where we need to pop into an inline approval flow with custom elements and controller actions. How do you hook the existing platforms for this? There zero path. MCP can give you an information channel, but it does not enforce the required UI/UX flow for certain tool calls. We could either compromise on UX or rebuild chatgpt.com from scratch. We ultimately went with the latter.