What makes the site quietly odd is not just its age but what it gave up when excavated: no human remains at all, despite being a monument type that archaeologists associate almost entirely with communal burial. Court tombs, built around 4000 BCE or earlier, typically consist of a roofed stone gallery divided into burial chambers, fronted by an open semicircular or oval forecourt where ritual activity is thought to have taken place. Here, both elements survive in reasonable form, the two-chambered gallery running roughly northwest to southeast and divided internally by upright jamb-stones, with a circular court opening at the northwest end.

J. X. W. P. Corcoran excavated the site in 1964, and the results were puzzling in their restraint. The cairn, the mound of stones that would originally have covered the gallery, had been reduced to slight traces, and whatever the monument once contained had long since disappeared or was never deposited in the first place. What Corcoran did recover were two sherds of pottery, two flint javelin-heads, and a scatter of flint and chert scrapers and arrowheads. These are the kinds of objects associated with Neolithic life and ceremony, but they do not resolve the question of why no burial evidence survived. Whether the tomb was never used for interment, was cleared out at some point in antiquity, or simply yielded nothing to the spade after millennia of disturbance remains open. The site is further noted in scholarship by Richardson and Lowry Corry as far back as 1940, and was catalogued by Ruaidhrí de Valera and Seán Ó Nualláin in their 1972 survey of megalithic tombs.

What gives the Kilnagarns site an additional layer of interest is its immediate neighbourhood. Roughly twenty metres to the west-southwest stands a wedge tomb, a different monument type, generally considered somewhat later in the Neolithic or early Bronze Age, and about thirty-five metres to the east there is a standing stone. Three distinct prehistoric monuments in close proximity on a single drumlin top suggests this was not an accidental or isolated choice of location. Whether that concentration reflects a long continuity of use, a deliberate grouping, or simply the practical appeal of elevated ground, the hilltop evidently held some significance that outlasted any single generation of its builders.