Indicate that thing needs user action to work

There are things in the platform that can only succeed because of some user action. For example, directly calling:

document.body.requestFullscreen();

In Gecko, results in the following warning:

⚠️  Request for fullscreen was denied because Element.requestFullscreen() 
was not called from inside a short running user-generated event handler.

Would it be useful to have some means of annotating such behavior using WebIDL?