How can i make a variable change to true or false when left mouse is pressed?

Hi, im trying to make a T-pose animation (like the one in JToH) and i couldn't find how to check for mouse inputs. I'm really new to Lua, but i have some experience with C+ and GML. I could get as far as this:

active = false
script.Parent.Equipped:connect(function()
	active = true
end)
script.Parent.Unequipped:connect(function()
	active = false
end)

(This is on a tool by the way. Sorry for my inexperience, i searched for a long time but this is my last resort.)

make a remote event in replicatedstorage, rename it to itemequipped.

normal script in ServerScriptService:

if game.ReplicatedStorage.itemequipped:Fired()
	--do stuff
end

local script in tool:

active = false
script.Parent.Equipped:connect(function()
    active = true
end)
script.Parent.Unequipped:connect(function()
    active = false
end)
if active then
	game.ReplicatedStorage.itemequipped:Fire()
end

btw I might be wrong because I do not do much Fire() so most of this code is guesses but I want to help if I can.