Tool not activating even when equipped?

Problem:

It really helps when you organize your code. You had a few issues in your code. I outlined some errors below as comments:

local UIS = game:GetService("UserInputService")
local action = ""
local hum = script.Parent.Parent.Parent.Character.Humanoid -- Player and character should be variabled
local tool = script.Parent
local mouse = game.Players.LocalPlayer:GetMouse() -- Player could be a variable

UIS.InputBegan:Connect(function(input, istyping)
    local action -- This doesn't need to be here, it is overriding the previously defined 'action' making it irrelevant 

In your code, you should try to make a variable whenever you have to reference the same thing multiple times within the same scope.

Solution:

• Organize your code. It is useful to separate your code into different sections that share a common theme.
• Prevent unnecessary references by referencing once and storing the value in a variable.
• Paying attention to the scope and not overriding needed variables.

Fixed code:

This code was tested in Studio. It will work when placed in a LocalScript as a direct child of the tool.

--=== Services ===--

local UIS = game:GetService("UserInputService")
local Players = game:GetService("Players")

--=== Variables ===--

local action = ""

local Player = Players.LocalPlayer
local Character = Player.Character
repeat Character = Player.Character wait() until Character ~= nil

local hum = Character.Humanoid

local tool = script.Parent
local mouse = Player:GetMouse()

--=== Hooks (Connections) & Main Loop ===--

UIS.InputBegan:Connect(function(input, istyping)
    if not istyping and input.KeyCode == Enum.KeyCode.X then
        action = "Teleport"
        tool:Activate()
    elseif  input.KeyCode == Enum.KeyCode.R then
        action = "Donut"
        tool:Activate()
    elseif input.KeyCode == Enum.KeyCode.V then
        action = "KC"
        tool:Activate()
    elseif input.UserInputType == Enum.UserInputType.MouseButton1 then
        action = "Punch"
        tool:Activate()
    end
end)

tool.Activated:Connect(function()
    print(action)
    if action == "Teleport" then
        hum.Parent:MoveTo(mouse.Hit.Position)

    end
end)

Conclusion:

If you have any questions, or any more errors, you can contact me via Discord (phxntxsmic#2021).