By the time researchers were examining it in any detail, the enclosure had already been levelled, its earthworks reduced to grazing land. And yet enough information exists, across nearly two centuries of observation, to reconstruct something of what was once a substantial defended enclosure of the early medieval period.

On the Ordnance Survey six-inch map of 1842, the site appears as a hachured circular enclosure roughly 45 metres in diameter, with a stream cutting east to west across the southern half of the interior. By 1939, when P. J. Hartnett recorded his observations, the overall diameter measured approximately 200 feet, and the enclosing earthen bank still retained what he described as a good proportion of large stone alongside a shallow outer fosse, the term for a defensive ditch running outside the main bank. A drain crossed the site towards the south-east, and south of it the rampart had been largely erased, though Hartnett noted it remained traceable. Inside the enclosure, an arc of bank separated the north-east quadrant from the rest of the interior, suggesting a subdivision of the space within, perhaps for livestock, storage, or some other domestic arrangement typical of these farmstead enclosures. Also noted within that north-east quadrant was a possible souterrain, an underground passage or chamber of the kind often built beneath ringforts for storage or refuge, as well as a possible standing stone, though both features carry the uncertainty that comes with a heavily degraded site.

Ringforts, also known as raths, were the most common form of rural settlement in early medieval Ireland, typically enclosing a farmstead belonging to a family of some local standing. The Coolgarriff example, with its combination of stone-built bank, outer fosse, and internal subdivision, would have represented a reasonably well-appointed example of the type before agricultural activity gradually consumed it.