What makes Coolnagoppoge unusual is less the rath itself than the cluster of human activity surrounding it: three separate hut sites lie within fifty metres to the east and south-east, and a relict field boundary survives immediately to the west and south. Together they suggest not a solitary farmstead but something closer to a small early medieval settlement, now largely returned to rough grazing.

The rath is roughly circular, measuring 29 metres north to south and 28 metres east to west. Its enclosing earthen bank, about 3.6 metres wide, survives to an internal height of just over a metre, with an external fosse, a defensive ditch, running around part of the circuit and still measurable at 2.1 metres wide and 0.8 metres deep. Several gaps have opened in the bank over time, and a large stone protrudes from the outer face at the south-west. The interior slopes downward toward the north-west, and beneath the eastern half lies a souterrain, an underground stone-lined passage or chamber of the type commonly associated with Irish ringforts and thought to have served for storage or concealment. The Glashanaglarach stream, running along the northern edge of the site, is actively eroding the rath at its north-east arc, meaning the monument is measurably smaller today than it once was. Ringforts of this kind are generally dated to the early medieval period, roughly the sixth to tenth centuries, when they functioned as enclosed farmsteads for a family or small kin group.