This article explains how excavator attachment safety depends on complete coupler engagement, compatible pin geometry, adequate auxiliary flow, controlled supply and return pressure, correct tool settings, and verified mass and lift limits, then traces tool release, overheating, hose damage, unexpected motion, and instability to specific interface failures, while outlining the inspection, measurement, functional testing, configuration records, and post-shipment checks engineers need before approving each host-coupler-tool combination for sustained work across digging, lifting, demolition, grading, and other demanding industrial site applications.