NurseSim-Triage evaluates an agent's ability to perform safety-critical clinical triage in Emergency Department scenarios. The agent receives patient presentations (chief complaint, vital signs, demographics, medical history) and must assign the correct Manchester Triage System category (1-5) while providing clinical reasoning. Tasks assess: Risk Stratification - Correctly identifying life-threatening conditions (Category 1: Cardiac arrest, Anaphylaxis, Sepsis) Demographic Context Integration - Weighing age and gender as risk modifiers (e.g., chest pain in 72M vs 20M) Safety-Critical Decision Making - Avoiding dangerous under-triage that could delay life-saving treatment Clinical Reasoning - Explaining triage decisions with medically sound rationale The benchmark includes 15 gold-standard scenarios spanning all 5 MTS categories, evaluated by GPT-5.2 judges for both accuracy and safety complia