What are the key features of dreams that trigger dream recall in the waking state?
No recall happens when reading the description is probably because one is focusing on reading and visualizing it but not recalling. I think there are different key features to prompt recall for different dreams, since dreams are a mixture of several features, and their proportion or intensities varies in different dreams (Foulkes and Vogel, 1965). E.g., in a dream with intense emotion, emotion/feeling contributes more to the recalling while people, place account more for the recalling in a dream consists of events. 

Foulkes, D., &amp; Vogel, G. (1965). Mental activity at sleep onset. Journal of Abnormal Psychology, 70(4), 231.