Are cooked shrimp shells edible? Some Chinese shrimp dishes like the spicy garlic shrimp is served with the shell still on but head removed.  Since the shell was on during cooking, the seasoning is all over it.

Are you supposed to eat the whole shrimp with the shell, or remove the shell and only eat the meat?  I usually taste the seasoning on the shell and then peel it away to eat the meat only.
This depends partially on the cooking technique and the shrimp variety/size (=> thickness of the shell).

If the shrimp is deep fried the shell can turn crispy and is super fun to eat. However, if boiled, the shells are chewy and extremely unpleasant - in this case you have to peel them.

I am not familiar with the spicy garlic shrimp, but you can just try if the shell is crunchy, is pleasant to eat, and does not require excessive painful chewing - go for it, if not return to your old practice of pealing it and just licking the flavoring of the shells.