Captain reported the aircraft fuel quantity indicators were on MEL and during descent the right fuel tank indicator showed a rapid loss of fuel. After landing; the fuel tank was found to be empty with no evidence of a leak.

Narrative

Aircraft X has an MEL for fuel quantity indicator and when fueling aircraft; the quantity has to be verified manually. In ZZZ this procedure was accomplished and log book entry was entered. We flew the first leg ZZZ to ZZZ1 with no issues. We did the turn without taking on more fuel so no manual quantity check was required. Then we flew leg ZZZ1 to ZZZ2 in the descent the right fuel indicator started showing a rapid loss of the quantity of fuel in the right tank. (It went from the expected proper fuel level to 0 lbs in tank within 2 minutes) Since the MEL was specifically in place for this reason this quantity change was expected on the indicators no priority handling was requested. We continued on with the flight using normal procedures and landed with no incident. I showed the Maintenance Department the fuel indication after landing and which prompted them to check it manually to compare the quantity against the indicator and was found the right tank had no fuel in the tank. It should have had 600+ lbs remaining in tank. The aircraft was inspected for any signs of a fuel leak or residual fuel of any kind and none was found. Maintenance Control; Chief Pilot; and operations director we're all called and notified of the incident.MELS Pertaining to fuel need to be addressed asap. Better or more specific training and or procedures need to be in place to assure the aircraft has the appropriate amount of fuel.