It is currently unknown if they remain monogamous for life like many bigger parrots because of their isolated location, which is difficult to reach.

Adults of both sexes are green, have a yellow crown and undertail coverts, blue central tail feathers and brown eyes.

It has three subspecies: the nominate (M. k. keiensis), M. k. chloroxantha and M. k. viridipectus.

Juveniles of M. k. keiensis are generally duller in color; the other subspecies are as in adults.

Generally, they are approximately 9.5 cm (3.7 in) long and 11-14 g (0.4-0.5 oz) in weight.