I don't think it's supposed to be a sneaky steath ship rather it's a huge freaking battleship designed to bring a lot of firepower to bear.
Apologies in advance if this has been discussed elsewhere but is there any info/speculation on the small, roundish ship that the crew uses on Kronos? Captain's yacht maybe? A newer shuttle? A loaner from starfleet? A klingon ship they acquired/commandeered/stole?
It may be the civilian ship acquired in the Countdown to Darkness comic book.