Personally, I like a description which captures the point of the photo, how the photo works with the article, and anything in the photo that is specific to the article should be pointed out. The description does not need a lot of detail. For example, the alt text for my "morning Barking Translated" just says something like "a brown and copper hound dog stands on the back of a couch. She is mid-bark and the sunlight shines on her fur through the window." The article revolves around my dog and her constant barking out the window. I don't need the color of the house or what else can be seen around Chloe. The dog, her barking, and her standing on the couch are the point of the article so they are the point of the description in the photo. Thanks for asking! Enjoy your day!