A court tomb is a type of megalithic burial monument, typically consisting of a roofed stone chamber set within a long cairn, with an open semicircular or circular forecourt at one end where ritual activity is thought to have taken place. At Mullaghgarve, that forecourt survives as a grass-covered spread of cairn material, roughly oval in plan, though now reduced to low humps in the ground. Of the chamber itself, only two orthostats remain upright, one to the north and one to the south, the taller of them reaching just under a metre in height.

The most detailed picture of the monument comes not from any modern survey but from a description recorded in the Irish Folklore Commission's Schools' Collection, where a local man named Terrence Geoghegan recalled the tomb as it appeared before its destruction. He described limestone flags standing on end along the sides of a mound, with broken slabs inside that had evidently once formed a capstone roof spanning the chamber, and one taller stone at the western end. Crucially, he noted ashes outside that western stone, consistent with the kind of forecourt burning associated with ritual use at court tombs, and he recovered unburnt bones from within. The material he described did not survive long after his account was made. In 1936, the stones were taken and used in road-building, a fate that befell many megalithic monuments during that period of rural infrastructure work. Decades later, Terrence's grand-nephew, Mícheál Geoghegan (senior), was able to identify what little remained and brought it to the attention of the National Monuments Service. The cairn, extending roughly 21 metres east to west and 12 metres north to south, can still be traced, along with a line of four low kerbstones along its northern edge, though the monument as Terrence Geoghegan knew it exists now only in his written words.