They form an oval, roughly ten metres north to south and seven metres east to west, but they never quite close; the two arcs fail to meet at either end, leaving the enclosure open at both north and south. What purpose this incomplete oval served is not stated, and that ambiguity is part of what makes the place quietly arresting.

The enclosure sits within a much larger field system on the plateau, suggesting it was once part of an organised agricultural or pastoral landscape rather than an isolated feature. As described by Carey in 1999, the walls survive as little more than grassed-over mounds, just twenty centimetres high and fifty centimetres wide, the kind of dimensions that speak more to age and erosion than to any original modesty of construction. At the southern end, the western wall stops curving and runs straight for five metres towards the edge of the limestone scarp, almost as if it were pointing somewhere, or connecting to something that no longer survives. Further context is provided by the surrounding monuments. Around a hundred metres to the north-west lies a wedge tomb, a megalithic burial form typical of the late Neolithic and early Bronze Age in Ireland, characterised by a tapering stone gallery that is wider and higher at one end. Additional mound walls appear roughly a hundred and twenty metres to the north. The enclosure at Coolnatullagh is not a centrepiece but a fragment within a layered landscape that accumulated meaning and structure over a very long period.