Craugastor augusti adults are olive to gray-green to light brown with dark spots, often with light edges, dorsally. Juveniles have a prominent light band that darkens with age across the center of their backs. Their eyes are large and dark brown (Stebbins 1985, Schwalbe 1990). Males have dark tympana and during the breeding season, have dark throats, which become mottled in late summer. Females have white throats and pink tympana throughout the year (Goldberg and Schwalbe 2000). The snout-vent length for the species ranges from 5.0-9.5 cm (2.0-3.8 in) (Stebbins 1985). At Coronado National Memorial in Arizona, the mean size of females was 8.0 cm, while males were 7.2 cm (Goldberg and Schwalbe 2000). The frogs have a broad head and short legs, which gives them a squat, toad-like appearance. They have smooth skin and slender, unwebbed toes with prominent tubercles beneath the joints. Although they can make hops from boulder to boulder, they frequently walk in a stilted fashion with their hindquarters and heels off the ground. There is a fold of skin across the back of the head and a circular fold on the belly. Their tympana are semitransparent and smooth (Stebbins 1985, Schwalbe 1990).

It's range is Southern Arizona (Quinlan, Santa Rita, Patagonia, Huachuca, and Pajarito Mts.) and northeastern Sonora (Sierra El Tigre) south along the Pacific Coast foothills of Western Mexico.

These secretive frogs are terrestrial and are found in areas with limestone and other rock outcrops. The frog is nocturnal, spending the day under rocks, or in mines, wells, caves, or fissures (Stebbins 1985, Schwalbe 1990, Goldberg and Schwalbe 2000). When threatened, it inflates to several times its normal size. The skin fold on the belly may be useful in helping it to cling to the sides of caves. There is little life history information available. The longest documented lifespan of a wild individual is 5 years as an adult (Goldberg and Schwalbe unpublished data).

Advertisement calls of frogs from Arizona were significantly longer in duration, higher in frequency, and had longer duration pulses than those of frogs from either New Mexico or Texas; frogs from these later two sites were indistinguishable in these call variables (Goldberg et al. 2004). Their call is ventriloquistic, making them difficult to locate even after they are detected; most are located by their distinctive and loud “Walk-walk” or “Whaa-whaa- whaa-whaa” call. In Arizona, they call from their hiding spots (e.g. crevices) for only two to four weeks on rainy nights after the start of the summer monsoons in late June or July. Frogs call dependably for only two or three nights following the first heavy monsoon storm of the season (Rorabaugh, in AZ PARC 2006).

The diet consists of a variety of invertebrates.