A Study on Improving the Usability of an AI-Based Learning Tool to Support English Diary Writing for EFL Students

AI-based writing support systems are increasingly being explored as tools for supporting English writing in educational contexts. In English as a Foreign Language (EFL) settings, learners often need support in generating ideas, organizing content, receiving feedback, and revising written texts. However, AI-based writing tools should be carefully designed and evaluated to ensure their usability, reliability, and educational relevance before being implemented in authentic learning contexts. This study aimed to design and evaluate the educational usability of WriteOn, an AI-based writing support system for EFL writing tasks that integrates AI and natural language processing technologies, including GPT-API, NLTK, spaCy, and BERT. Although the system was initially designed to support English diary writing in EFL contexts, its feedback structure and system architecture were intended to be extensible to broader writing tasks. A formative usability evaluation was conducted with eight experts in South Korea with backgrounds in EFL instruction, educational technology, instructional design, and human–computer interaction. A structured questionnaire was used to assess the system’s effectiveness, efficiency, learnability, satisfaction, memorability, error prevention, and cognitive load minimization. Based on the expert evaluation results, the system was refined through an iterative design process. The findings provided preliminary evidence of WriteOn’s overall usability while identifying several areas for improvement, including clearer feedback, more consistent design features, and enhanced language support in grammar correction modules. In response, the system was refined to include topic and genre selection, rubric-based evaluation, and a more consistent interface. These results suggest that integrating generative AI and natural language processing technologies into EFL writing support can support the development of reliable, scalable, and learner-centered writing tools. The study also highlights the importance of iterative and formative usability evaluation in developing AI-driven writing support systems that promote instructional efficiency, feedback transparency, and learner-centered revision.