How would you animate a tool?

You can animate a tool.
You will need:
Some Scripting knowledge
A tool you would like to animate

To start off:
You need to take all of the baseparts (interact-able objects, e,g part, wedge, sphere, not scripts, values ect) in a model. One of the parts need to be called "FakeHandle" , this will be where you hold it. If you already have a part called Handle rename it to FakeHandle. Copy the fakehandle into workspace, as it is needed later.
Select the primary part of the model as FakeHandle.

Now you need an Animation Controller, unfortunately you cannot insert it right into the model straight away so you have to create it via script.
Insert a normal script into workspace. put this script inside it:

local a = Instance.new("AnimationController")
a.Parent = game.Workspace

Play the game, open workspace and copy the animation controller.
Stop playing the game.
Delete the script.
Paste the Animation Controller into the model.
Call it AC. Then use the custom character creator plugin to make the rig (tool).
CUSTOM CHARACTER CREATOR.
If you don't know how to make a rig, I recommend you watch this video, Please keep in mind YOU DO NOT NEED A HUMANOID ROOT PART. Its not using a humanoid.
video
Then download the animation plugin.
here...
make some animations.... lol

Then the scripting...
Create a tool and put the model you made earlier in the tool. Call the model "MovingParts". Insert a part into the tool called"Handle", DO NOT insert it into the model. The handle needs to be in the same position as the "Fake Handle"., it doesn't have to be perfect, though.
Insert a Local Script into the tool.
use this script...:

--Gun is the part of the gun that contains: Handle, Values and Scripts
local Gun = script.Parent
--AnimGun is a model because its a Rig, So it can be animated
local AnimGun = Gun:WaitForChild("MovingParts")

--Fake Handle (used in animation)
local FHandle = AnimGun:WaitForChild("FakeHandle")
--Real Handle (Used to hold tool)
local RHandle = Gun:WaitForChild("Handle")
--Make a table of the elements in MovingParts
local guntable = AnimGun:GetChildren()

--Make a weld from Real to Fake handle, parent weld to Real Handle
local HandleWeld = Instance.new("Weld",RHandle)
HandleWeld.Part0 = RHandle
HandleWeld.C0 = RHandle.CFrame:inverse()
HandleWeld.Part1 = FHandle
HandleWeld.C1 = FHandle.CFrame:inverse()

--Animating Part

local AnimationController = AnimGun:WaitForChild("AC") --Equivilent to Humanoid, instead used for animating NPCs
local Animation = Instance.new("Animation")
Animation.AnimationId = "https://www.roblox.com/Asset?ID=000000001" --Put the animation ID here
local LoadAnimation = AnimationController:LoadAnimation(Animation) --Loads the Animation
print("Loaded the Animation")
function onKeyPress(actionName, userInputState, inputObject) --Function for playing animations
    if userInputState == Enum.UserInputState.Begin then
        LoadAnimation:Play() --Plays the animation
        print("Animation played")
    end
end

game.ContextActionService:BindAction("keyPress", onKeyPress, false, Enum.KeyCode.R) --when r pressed does function

should work