How do I make it so my script only works when someone is holding a certain tool?

I'm trying to fix something which is taking me ages, basically- I'm trying to make it so that a script of mine only works when I have a certain tool in my hand.

model = script.Parent.Parent

backup = model:clone()
enabled = true


function regenerate()
 model:remove()


 wait(1)--


 model = backup:clone()
 model.Parent = game.Workspace
 model:makeJoints()


 script.Disabled = true
 script.Parent.BrickColor = BrickColor.new(26)--Black
 wait(1)
 script.Parent.BrickColor = BrickColor.new(104)--Purple
 script.Disabled = false
end


function onHit(hit)
 if (hit.Parent:FindFirstChild("Humanoid") ~= nil) and enabled then
  regenerate()
 end
end


script.Parent.Touched:connect(onHit)

it is easy. just do this,

copy this script to the moving part inside the tool. so script.Parent is the moving part in that tool. when it touches something, do that onHit() thing!

but then, you need to fix something. model is, of course, not a script.parent.parent anymore, it has to be derived from workspace.