In regards to the size of the tags and if they are appropriate for your hens, does your local ordinance require they be displayed? If not, then I would toss those in the paperwork bin personally.
Vernon's Texas Health and Safety Code does specify that current rabies will be displayed and it is a class c misdemeanor per animal found in violation, just for a comparison. If your hen's do wander it might be kind of fun to tag them:

I can visualize someone on the phone letting animal control know their hen responds to(in our case it is Red and Polly)...... or explain that you have a special needs hen, who will only eat dry cat kibble if hand fed, otherwise, OSHA requires hearing protection for anyone within 100 feet.......