[2][3][4] However, as of late 2024 BirdLife International's Handbook of the Birds of the World retains the "pygmy-tyrant" common name for it.

Their throat is white and the rest of their underparts mostly pale yellow; the sides of their breast, flanks, and undertail coverts are deep warm ochraceous buff.

[6] The rufous-sided scrub tyrant's diet has not been detailed but is known to be mostly arthropods and also includes significant amounts of small fruits.

The rufous-sided scrub tyrant's principle vocalization is a "sustained, toneless, fast, dry rattling 'pe-tit-rrut- -' or 'tit-tit-=tit-rrrut' ('tit-tit' staccato)".

[7] It also makes buzzy trilled alarm calls and a "higher, more squeaky rattling chatter; or a screeching, strained clee-clee, also in [a] longer series".

[6] The IUCN originally in 1994 assessed the rufous-sided scrub tyrant as Vulnerable, then in 2004 as Near Threatened, and since July 2024 as being of Least Concern.