It is a holy well, a spring enclosed within a wedge-shaped structure built of roughly coursed limestone blocks, heavily mortared and roofed with three broad flat lintels. Five stone steps lead down to the water, the passage narrowing as it goes, from just over a metre wide at the entrance to half a metre at the back. The whole thing measures only 1.4 metres from front to rear. It is an intimate, almost secretive piece of construction.

The well carries two names. Tobermacduagh connects it to Saint Mac Duagh, also known as Colman Mac Duagh, a sixth and seventh-century monastic founder closely associated with the Burren and the diocese of Kilmacduagh, whose ruined cathedral and famous leaning tower stand some distance to the south. The second name, Cloghannanack, is harder to parse but suggests a local placename tradition running alongside the saintly dedication. Holy wells of this kind were typically focal points for patterns, the seasonal gatherings of prayer and communal assembly that were once a widespread feature of Irish rural life, and the presence of a whitethorn bush growing close by to the south is quietly significant. Thorn trees near holy wells were traditionally used for leaving votive offerings, scraps of cloth or other tokens tied to the branches as part of a devotional act. No offerings were recorded here at the time of survey, though the bush itself remains.