The main structure is a rectangular tower house, rising three storeys high and built from roughly coursed sandstone rubble. Its walls feature a distinctive high base batter; a sloping foundation that helped defend against undermining during sieges. Today, nineteenth-century outhouses partially obscure what appears to have been a bawn, or fortified courtyard, that once extended to the north and west of the tower.

The castle's history stretches back to at least the early seventeenth century, when John Ryan held it as proprietor in 1640. By the time of the Civil Survey in 1654-6, following the Cromwellian conquest of Ireland, the structure was already showing signs of decay. The surveyors recorded it simply as 'the walls of a castle and a Barbicon', suggesting that while the main defensive features remained standing, the castle may no longer have been habitable or fully functional as a residence.

Like many Irish tower houses, Cragg Castle represents the defensive needs and social aspirations of the Gaelic and Old English gentry during the late medieval and early modern periods. These compact fortified residences served both as symbols of status and practical strongholds in an often turbulent landscape. The addition of the bawn would have provided space for cattle and followers during times of conflict, making the castle a self-contained defensive unit capable of withstanding raids and minor sieges.