There are several reasons why your sugar cookies may be too crispy and dry. You may have over-baked them, which caused too much of the liquid from the butter or shortening and the eggs to evaporate, or you could have left them uncovered for too long. The key to softening hard sugar cookies is to return some of the moisture they lost.
If your sugar cookies have turned crispier than you like during storage, add a slice of fresh bread or a piece of a juicy apple to the container and seal it tightly. The cookies will absorb the moisture from the bread or apple and become softer. You can include a piece of bread or apple when storing all types of cookies to keep soft cookies soft and crispy cookies from becoming hard and unappetizing.
Don't Overdo It