Swainsona brachycarpa is a prostrate or ascending herb, that typically grows to a height of less than with many slender stems arising from its base. Its leaves are imparipinnate, long with
stipules long at the base. There are 9 to 13 egg-shaped to narrowly elliptic or egg-shaped leaflets, mostly and wide. The flowers are arranged in racemes long of up to 12, usually only up to 2 flowers open at any one times, on a
peduncle up to in diameter, each flower long. The
sepals are softly-hairy and joined at the base, forming a tube long, the sepal lobes shorther than the sepal tube. The petals are white, purple or dark red, the
standard petal about long, the
wings long, and the
keel mostly long. The fruit is usually an elliptic
pod long and wide with the remains of the
style long. ==Taxonomy and naming==