Like most of the Calimmon Garrisons, this non-elaborate fortress was built from huge stones. Its walls were ten-to-fifteen-feet thick (3.0–4.6 meters) and 20 feet high (6.1 meters) with a deep, empty moat around them.
Due to its proximity to one of Calimshan's major cities and one of its most dangerous ruins, Fort Agis was defended with a greater complement of troops than its sister garrisons. Around 300 Tethyrian soldiers were stationed there.
The four primary Calimmon Garrisons were: