Every MCP tutorial puts the server on a server. They don't have to. If your app already has the data, the auth, and the UI state, why are you copying it to a backend just so an agent can reach it? The future of the web is agentic, and it belongs to the client side.
In this talk, I will show how the Prompt API and WebMCP enable a different architecture: the page exposes its own tools, an on-device model discovers and invokes them autonomously. You chat with the local model, it decides which browser tool to trigger, aggregates the data, and renders the result. No backend LLM. No API tokens. Zero operational cost.
