The ringfort itself is unremarkable enough by Irish standards, a roughly circular enclosure measuring about 37.8 metres east to west and 37.4 metres north to south, but just north of the centre sits a low oval mound, 3.5 metres by 1.2 metres and barely 30 centimetres at its highest point. It is too deliberate to be a trick of the land, and too small to be easily explained away. Whether it is a buried feature, a later addition, or something older than the fort itself is not recorded.

Ringforts, known in Irish as raths when built from earth rather than stone, were the most common form of rural settlement in early medieval Ireland, typically dating from roughly the fifth to the twelfth centuries. They functioned as enclosed farmsteads, the bank and fosse (a drainage or defensive ditch encircling the outer edge) marking the boundary of a household's territory as much as providing physical protection. At Coolrus, the earthen bank survives to an internal height of about 65 centimetres and an external height of just over a metre, with the outer fosse running to around 2.45 metres wide and 40 centimetres deep. A gap of approximately 2 metres in the western side of the bank marks what was almost certainly the original entrance. The site was compiled by Denis Power and uploaded to the record in August 2011.

The site lies in agricultural pasture, which means access depends on the usual courtesies of the Irish countryside, identifying the landowner and seeking permission before crossing private land. Because the earthworks are low and the surrounding ground is flat, the fosse and bank are best read from inside the enclosure rather than at a distance. The oval mound just north of centre is subtle enough to be missed on a casual walk-through, so it is worth moving slowly once inside and looking at ground level across the interior. The features are grass-covered and unlikely to show dramatically in summer growth; a low winter sun or early morning light will cast enough shadow to make the slight undulations legible.