I dont think the firefighting needs are under question. Each airport declares its firefighting capability so regardless of how much fuel is onboard an aircraft you will (should) get every fire truck available should you ever need them.

As mentioned above the fuel figure is related to endurance. Not sure if you can declare fuel in time or if it has to be a pound/kilogram figure.

Having had this situation, ATC initially asked our PoB and fuel endurance on arrival (time).
Slightly later, questions came in which were geared more to containment of any further issue on the ground- fuel quantity in Kilos, and nature with specific location of dangerous goods.