The Long-billed Starthroat is marked by a long, straight bill and white markings on the cheek and tail tips. The Bolivian account describes it searching vegetation at different heights and darting after flying insects.
The bill is long and straight. White markings cross the cheek and tail tips, and partly concealed white lines run along the sides of the lower back.
The Birds of Bolivia account says it feeds at different levels of vegetation and perches openly in the upper foliage. It launches from a perch to catch flying insects.
The bill is 3.2–3.5 cm long.
An extinction-risk assessment has not been added yet.