WebMCP

/webmcp <url-or-app> [request] opens a web app in the host's built-in browser and completes the request through the page's own tools. The first token is a URL or an app alias; the rest is the request.

/webmcp slides make me a new deck about customer onboarding

The two rules

Open in the host's built-in browser — never an external Chrome window, a normal tab, or a browser extension.
Call the page's tools. Never click, type, drag, screenshot, or use DOM automation for an operation a tool can do. UI controls are for navigation and visual inspection only.

That is the whole contract. Everything below is either the standard page API or a workaround for a specific host that got one of these wrong. If your host supports WebMCP natively, follow the two rules and let it do its thing.