Equip is not a valid member of Tool. Can anyone help?

Roblox says Equip is not a valid member of tool, but it clearly is. This is the script that changes the BoolValue of Equipt:

local tool = script.Parent

local function onEquip()
    tool.Equip = true
end

local function onUnequip()
    tool.Equip = false
end

local function onActivate()
end

local function onDeactivate()
end

tool.Equipped:Connect(onEquip)
tool.Unequipped:Connect(onUnequip)
tool.Activated:Connect(onActivate)
tool.Deactivated:Connect(onDeactivate)

Here's Equip being a valid member of Tool: I would really appreciate if someone could help me with this.