Jailbreak Assessment via Decompositional Scoring (JADES) is a general-purpose framework for evaluating jailbreak success, designed to improve upon existing inaccurate and subjective assessment methods. It decomposes harmful questions into weighted subquestions and scores each subanswer to arrive at a final decision. Additionally, it can optionally include a fact-checking module to enhance hallucination detection. In this paper, we present a new benchmark, JailbreakQR, consisting of 400 jailbreak prompt-response pairs, and validate JADES against it. JADES achieves 98.5% agreement with human raters, demonstrating over 9% improvement over existing methods and exposing the problem of overestimation in existing assessment methods.