Tool editor

some questions about that interface, where should be buttons for adding input/output/parameter (one suggestion is in the newDesignQuestions.png) and what about parameter which type is enum? i think maybe a small table with two columns would be ok, what do you think?.

and for adding a new for example parameter, should pop up a modal window called something like New Parameter and where you can create it, or should it appear directly to that main window?