The bird's feathers are a deep blue and there is a distinctive blue oval area around the eye which is free of feathers. Like all cuckoos they have large feet, with a reversible third toe. It has a bulky silhouette and short, broad wings and long tail, all of which can be seen when gliding between trees. The average size of the birds is 48 to 50 cm (18.9 to 19.7 in) in length and 30 to 60 grams (1.1 to 2.1 ounces) in weight with the females slightly larger. The calls are evenly spaced ″koa koa koa ″ notes and a brief ″brreee ″.
The blue coua is an omnivore eating insects, fruits and small reptiles in subtropical or tropical dry forest, subtropical or tropical moist lowland forest, subtropical or tropical mangrove forest, and subtropical or tropical moist montane forest. The females lays one white egg on a platform nest, constructed of leaves and twigs on a trees branch.