The E-Bench framework offers a comprehensive evaluation methodology for assessing the usability of large language models (LLMs). It introduces controlled variations to measure robustness and adaptability, providing data-driven guidance for selecting and deploying models for generative AI. The framework comprises several interconnected technical components that work together to deliver standardized evaluations. These include data selection and domain categorization, perturbation generation, performance measurement, and analysis frameworks. By systematically measuring model robustness against real-world input variations, organizations can gain critical insights that directly impact deployment success and user satisfaction. E-Bench complements traditional performance benchmarks, adding a critical dimension to the evaluation process. It addresses the gap between impressive benchmark scores and actual user experience, enabling organizations to deploy AI systems that perform reliably in real-world settings.