Red-eyed Tree Frogs (Agalychnis callidryas), as their name implies, have red eyes with vertically narrowed noses, a vibrant green body with yellow and blue striped sides and bright orange feet. There is a great deal of regional variation in flank and thigh coloration.

Males range from 2 (5.08 centimetres) to 2½ inches (6.35 centimetres), while females range from 2½ (6.35 centimetres) to 3 inches (7.62 centimetres) on average. Young frogs are typically brown in color and turn greener as they mature, although adult frogs can change their color slightly depending on mood and environment. Red-eyed tree frogs have soft, fragile skin on their stomach, and the skin on their back is thicker and rougher.

The red-eyed tree frog has three eyelids and sticky pads on its toes. Phyllomedusid tree frogs are arboreal animals, meaning they spend a majority of their life in trees, which also makes them great jumpers.

Red-eyed tree frogs are not poisonous and rely on camouflage to protect themselves. During the day, they remain motionless, cover their blue sides with their back legs, tuck their bright feet under their stomach, and shut their red eyes. Thus, they appear almost completely green, and well hidden among the foliage.