Codehints for your own classes?

How is it possible to get codehints for classes that you have made or downloaded? I tried the program “Primalscript” and it makes a template class structure when you begin a new class where codehints and other stuff where declared in comments… Is that the way to go, and if so - how?

I would like to get the parameters that are needed for certain classes to popup in that yellow little textbox as you type for instance:

“Math.round(”

You’ll get a popup textbox saying “Math.round(number)”.