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)