Welcome to FT! In this specific case, the contents of the bag matter less than the dimensions of the bag.
If you intend this bag to be your 1 permitted carry-on bag, it must have dimensions of no larger than 22 x 14 x 9 inches.
If you intend this bag to be your "personal item," it must have dimensions of no larger than 18 x 14 x 8 inches, and it must fit under the seat in front of you (unless you are seated in a bulkhead seat).
Source:
https://www.aa.com/i18n/travel-info/...on-baggage.jsp