AISC Specification for Structural Joints Using ASTM A325 orn A490 Bolts
Bolt Geometry." The lenght of of bolts shall be such that the end of the bolt will be flush with or outside the face of the nut when properly installed".
He should not require a bolt any longer than required to meet the above requirement.
Depending on the type of connection i.e. threads included in a shear plane, threads excluded, slip-critical, if the bolt is to long you could exceed the thread lenght and run into the thread run-out( the shank of the bolt without threads). If this occurs, validation of required tensioning is questionable.
Washers are not required for all connection using A325 or A490 bolts.
When washers are required they should be kept to a minimum (2)one under nut and one under bolt head if required.