How to use a tool in Roblox Studio? HELP PLEASE

I Put the tool in the starter pack and I wanted to make the Local script only work when the tool is selected. The local script I have is for a wave of water. What Do I have to do add a Handle?

local enabled = true
Player = script.Parent.Parent
--Player:WaitForDataReady()
mouse = Player:GetMouse()
run = game:GetService("RunService")
function onKeyDown(key)
if not enabled then return end
enabled = false
    Key = key:lower()
    if key == "x" then
        RightShoulder = Player.Character.Torso["Right Shoulder"]
        LeftShoulder = Player.Character.Torso["Left Shoulder"]
        Run = game:GetService("RunService")
        for i = 1, 2 do
            for i = 1, 12 do
                LeftShoulder.C0 = LeftShoulder.C0 *CFrame.Angles(0, 0, -0.16)
                RightShoulder.C0 = RightShoulder.C0 *CFrame.Angles(0, 0, 0.16)
                RightShoulder.C0 = RightShoulder.C0 *CFrame.Angles(0, 0.1, 0)
                LeftShoulder.C0 = LeftShoulder.C0 *CFrame.Angles(0, -0.1, 0)
                Run.Stepped:wait(0.01)
            end
            for i = 1, 12 do
                LeftShoulder.C0 = LeftShoulder.C0 *CFrame.Angles(0, 0.1, 0)
                RightShoulder.C0 = RightShoulder.C0 *CFrame.Angles(0, -0.1, 0)
                LeftShoulder.C0 = LeftShoulder.C0 *CFrame.Angles(0, 0, 0.16)
                RightShoulder.C0 = RightShoulder.C0 *CFrame.Angles(0, 0, -0.16)
                Run.Stepped:wait(0.005)
            end
        end
            for i = 1, 12 do
                LeftShoulder.C0 = LeftShoulder.C0 *CFrame.Angles(0, 0, -0.16)
                RightShoulder.C0 = RightShoulder.C0 *CFrame.Angles(0, 0, 0.16)
                RightShoulder.C0 = RightShoulder.C0 *CFrame.Angles(0, 0.1, 0)
                LeftShoulder.C0 = LeftShoulder.C0 *CFrame.Angles(0, -0.1, 0)
                Run.Stepped:wait(0.005)
            end
        game:GetService("Chat"):Chat(Player.Character.Head, "Water Style: Water Wave Jutsu")
        x = Instance.new("Part")
        x.BrickColor = BrickColor.new("Really Blue")
        x.Size = Vector3.new(15, 10, 2)
        x.TopSurface = "Smooth"
        x.BottomSurface = "Smooth"
        x.Shape = "Block"
        x.Name = Player.Name
        x.CanCollide = true
        x.Transparency = 0.1
        fd = script.Waterdamage:clone()
        fd.Parent = x
        y = Instance.new("BodyVelocity")
        y.maxForce = Vector3.new(math.huge, math.huge, math.huge)
        y.velocity = Player.Character.Torso.CFrame.lookVector*80
        x.Parent = Workspace
        y.Parent = x
        f = Instance.new("Fire", x)
        f.Size = 15
        f.Heat = 0
        x.CFrame = Player.Character.Torso.CFrame*CFrame.new(0, 0, -6)
        fd.Disabled = false
        game.Debris:AddItem(x, 6)
        wait(0.25)
        for i = 1, 12 do
            LeftShoulder.C0 = LeftShoulder.C0 *CFrame.Angles(0, 0.1, 0)
            RightShoulder.C0 = RightShoulder.C0 *CFrame.Angles(0, -0.1, 0)
            LeftShoulder.C0 = LeftShoulder.C0 *CFrame.Angles(0, 0, 0.16)
            RightShoulder.C0 = RightShoulder.C0 *CFrame.Angles(0, 0, -0.16)
            Run.Stepped:wait(0.01)
        end
    end
wait(0)
enabled = true
end

mouse.KeyDown:connect(onKeyDown)