The black-capped pygmy tyrant is a tiny short-tailed bird, 6.5 cm long, and weighing 5.2 g. The crown is black, shading to dark grey on the rest of the head, and contrasting with the white “spectacles”. The rest of the upperparts are olive-green.
The black-capped pygmy tyrant is a tiny, short-tailed bird, measuring 6.5 cm in length and weighing 5.2 grams. Its crown is black, transitioning to dark grey on the rest of its head, contrasting with the white "spectacles". The remaining upperparts are olive green.