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.
Rescue Efforts
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
Because cookies take up very little space on the baking pan, they bake much more quickly than other types of denser pastries, and it's very easy to overshoot the doneness mark. You can prevent cookies from over-baking by taking them out of the oven one or two minutes before the minimum recommended baking time, as they will continue to bake on the hot pans before they begin to cool. Even if the centers appear puffy and wet, they will collapse and bake through.