So how do i make a when key pressed?

So when key q is pressed i want my tool transparency to change to 1 but when its already at 1 then it and q is pressed then it changes to 0

Extending on that comment, look into UserInputService.

Here is an example of how its setup:

function onInputEnded(key)
	if key.KeyCode == Enum.KeyCode.Q then
		-- Do stuff
	end
end

game:GetService('UserInputService').InputEnded:Connect(onInputEnded)

This event returns an InputObject as the first parameter. You can use the .KeyCode property to check if the player has pressed a certain key.

As for the toggling of visibility, an easy trick is to use a boolean to check its current state.

you can use else if statement with the transparency