Clear["Global`*"]
Create a wrapper for adding a Tooltip to a Quantity
qTooltip[q_Quantity, tt_String] :=
Tooltip[QuantityForm[q, "Abbreviation"], tt]
Like other wrappers (e.g., MatrixForm), the wrapper should not be included in variable definitions.
qTooltip[quant = Quantity[1, "Month"], "how to make it work?"]
(* Tooltip[1*"mo", "how to make it work?",
TooltipStyle -> "TextStyling"] *)
The definition of quant does not include the wrapper.
QuantityMagnitude[quant]
(* 1 *)
UnitConvert[quant, "days"]
(* Quantity[365/12, "Days"] *)