The chamber is D-shaped in plan, its straight southern wall pierced by a low lintelled ope, a narrow doorway topped with a flat stone, just 0.6 metres wide and 0.8 metres high. Beside the entrance, set into the eastern wall, is a small niche. This is Tobermacduagh, a holy well dedicated to St Mac Duagh, and it has been drawing visitors for long enough to appear by name on the Ordnance Survey six-inch maps of both 1842 and 1915.

Holy wells in Ireland typically mark places of pre-Christian or early Christian veneration, later absorbed into the cult of a local saint. This one is associated with Mac Duagh, a sixth-century monastic founder whose principal church lies roughly fourteen metres to the south-west. That complex is a dense one: two penitential stations, a hermitage cave, a possible bullaun stone (a boulder with one or more cup-like hollows, traditionally used for grinding or ritual purposes), and a graveyard are all clustered within what may originally have been a single enclosing boundary, though the hazel growth makes that outer boundary difficult to trace now. When the well was surveyed in 1997, the small niche inside the chamber held a deposit of oyster shells, an offering that speaks to the well's long role as a devotional site. By 2016, ribbons tied to a nearby tree had become the dominant form of votive offering, a practice known in Irish as clootie-tying, in which strips of cloth are left as petitions or tokens of thanks.

The well sits in a forest setting, and the surrounding monastic remains reward a careful, slow look rather than a quick pass. The lintelled entrance to the well chamber is low enough to require stooping, and the interior, at roughly 1.3 by 1.2 metres, is intimate in scale. The drystone walling stands about 1.8 metres high over the interior, solid and carefully built. The ribbons on the nearby tree mark the spot from a little distance.