The building is a nineteenth-century Gothic Revival structure, complete with dressed limestone blocks, projecting corner buttresses, and pinnacles capping each corner. A corbelled rubble-stone roof, a pointed-arched doorway, and a gable with dressed stone copings: it is, in short, a miniature piece of ecclesiastical-style architecture built around a natural spring and a partially quarried rock pool measuring roughly one and a half metres by one and a half metres and barely twenty centimetres deep. To enter, you step over a low blocking stone, pass through the pointed arch, and descend three steps to reach the water.

The well has been known by several names across the centuries, which itself hints at a long, layered local significance. It appears as Tobercornan on both the 1842 and 1915 Ordnance Survey six-inch maps, and Tim Robinson's 1977 map of the Burren records it under two names: Pinnacle Well, a clear nod to the buttress caps of the wellhouse, and Tobar Chornáin, the Irish form. The origin of Cornán is genuinely uncertain. Writing in 1980, Cunningham suggested it might derive from the Irish word for Pennywort, a low-growing plant common in damp, rocky places, or it might commemorate a person named Cornan. Holy wells in Ireland frequently carry the names of early saints or local figures now largely forgotten, and this one preserves an ambiguity that has so far resisted tidy resolution. The spring itself rises from the higher rocky ground immediately to the south of the road, feeding the pool naturally, and the whole structure sits at the boundary between geology and human devotion that the Burren does so quietly and so well.