Information on the parameters expected by a method can be displayed in a tooltip when you are calling that method. The tooltip is triggered by the opening bracket ( and the highlight moves from one parameter to the next as the separating commas are entered. The return type of the method is also shown. By default all parameters are shown as instances of the Object class. If the return type can be inferred, its class is shown, otherwise NilClass is shown. To enable more descriptive information in Parameter Info tooltips, consider using Type Assertions.