[weba11y]

It should probably do something when you type & hit the 'enter' key (even if its just a dialog asking what search engine you'd like to use).

Or maybe I am missing something, as you said you it can used with just a keyboard. I'm on Chrome...

[WiggleGuy]

Yes: engines have shortcuts associated with them. So the shortcut for Google, for example, is g. If you type something in, press enter, then just press g, it will forward your search to Google.

You can tell what shortcut an engine has by the underlined letter (or the letter in square brackets).

I'll add in a prompt.