I use the anode hole. After you get it in shape I just use water, nothing else. But I usually flush out 2 or 3 times a year. The newer clean out tools are now plastic. If possible get the copper tube model or make one yourself. I was able to aim and clean out better with metal tube than plastic tube. Lots of videos and info about it. I keep mine stored inside water heater door along with spare anode.
I do mine when water is cold...sounds simple enough...but I learned that one by mistake the hard way. Hot water really is hot:) Many times I also sanitize afterwards. I usually replace the anode if 1/2 gone or better.
After you think you are done...fill up 3 clear glasses of water and let sit on table for couple hours. Then look real close at glasses to see water is 100 percent clear and no little creatures on the bottom. Like little calcium crums. Reason to check is those little crums make their way to water pump and faucets. Not your best friend.
