In my experience the HR Irvine does cover tip (up to 15 %). Anything over that is the guest's responsibility. I like that property, and I usually leave about 18 % for a tip. They are quite generous for breakfast on Monday mornings when the RC is closed if they do not have a buffet that day. I was told that I could order as much as I want off the menu when I asked about any limits on the diamond breakfast.
I am not going to lose any sleep over having to cough up an extra $.50 cents a day for a tip at the HR Irvine.