MARQ: A Modular, LLM-Agnostic Requirement Quality Assessor Infused with Systems Engineering Knowledge A modular, LLM-agnostic requirement quality assessor called MARQ, which supplements large language models with a criterion-specific knowledge stack operationalizing INCOSE requirement quality criteria, raised median F1 scores on an expert-labeled NASA requirement set across three models over 100 executions each, according to the arXiv paper 2610.36234v1. MARQ scored median F1 of 0.80 for Claude Opus 5, 0.62 for GPT-5.6 Sol, and 0.53 for Gemma 3 12B, versus off-the-shelf baselines of 0.55, 0.52, and 0.18 respectively. The authors report the gains are model-dependent — Claude Opus 5 improved defect detection and false-alarm control, GPT-5.6 Sol gained detection and execution-level consistency at the cost of more false alarms, and Gemma 3 12B matched off-the-shelf proprietary models while remaining highly variable — with improvements concentrated in Correctness and Conformance criteria. arXiv:2610.36234v1 Announce Type: new Abstract: Requirements engineering RE is foundational to systems engineering SE , as requirement defects can propagate downstream and adversely affect development outcomes. Although large language models LLMs are promising for requirement quality assessment, prior work shows that off-the-shelf models miss a large share of expert-identified defects, perform unevenly across quality criteria, and vary across executions. This study investigates whether infusing expert-derived SE knowledge can improve LLM-based requirement quality evaluation beyond off-the-shelf capability. We present MARQ, a modular, LLM-agnostic prototype that supplements LLMs with a criterion-specific knowledge stack operationalizing INCOSE requirement quality criteria and evaluated against off-the-shelf baselines on an expert-labeled NASA requirement set using Claude Opus 5, GPT-5.6 Sol, and the open-weight Gemma 3 12B, with 100 executions per model. MARQ achieves median F1 scores of 0.80 for Claude Opus 5, 0.62 for GPT-5.6 Sol, and 0.53 for Gemma 3 12B, compared with off-the-shelf baselines of 0.55, 0.52, and 0.18, respectively. However, the nature of these gains is model-dependent. Claude Opus 5 improves defect detection and false-alarm control; GPT-5.6 Sol gains detection and better execution-level consistency at the cost of more false alarms; and Gemma 3 12B reaches the performance of off-the-shelf proprietary models, although it remains highly variable. Criterion-level analysis shows gains concentrated in Correctness and Conformance, trade-offs between misses and false alarms within individual criteria, and model-dependent responses across several criteria. These findings position SE knowledge infusion as a promising model-agnostic pathway for strengthening trustworthy LLM-based RE support while underscoring the need for criterion-specific interventions and human-in-the-loop review.