A small, sunbirdlike bird of montane forest. Long, thin, curved bill and olive body with slaty wings, head and contrasting yellow, lower throat. Similar to several other species, but Slaty-chinned Longbill lacks the gray chest of Spectacled Longbill and female Black Sunbird, lacks the yellow eye-brow of female Olive-backed Sunbird and has a contrasting gray head and yellow throat, unlike the lower elevation Yellow-bellied Longbill. Song, a high-pitch jumble of slurred notes sometimes interspersed with loud downward “chew!” calls.