Context-Aware Workflow Decomposition for Automated Mobile UI Annotation Using Multimodal Large Language Models
For researchers and practitioners in mobile UI understanding, this work provides a practical workflow design strategy to improve annotation reliability using multimodal LLMs.
This paper investigates automated mobile UI annotation by decomposing the task into context-aware stages, finding that a two-step workflow achieves the highest precision, while deeper decomposition improves recall but increases false positives.
Accurate mobile user interface annotation is important for UI understanding, accessibility tools, automated testing, dataset construction, and GUI agents. However, mobile screens are difficult to annotate because they often contain small, dense, nested, and visually ambiguous elements. Multimodal large language models can help automate this process, but their outputs are sensitive to prompt design and the organization of annotation tasks. This paper studies automated mobile UI annotation from a workflow design perspective, focusing on improving annotation precision. Rather than asking the model to annotate all UI elements in a single step, the task is divided into smaller context-aware stages, allowing related UI elements to be handled with clearer instructions and useful screen context. The proposed pipeline uses structured prompts, schema-constrained JSON outputs, and element-specific annotation instructions. Experiments are conducted on expert-annotated mobile UI screens from the MUIAnno dataset, using eight common UI element types: button, tab, clickable text, card, label, plain text, icon, and image. Four workflow strategies are evaluated: one-step, two-step, four-step, and eight-step annotation. Results show that the two-step workflow achieves the highest precision, while deeper decomposition improves recall but produces more false positives. Additional grouping experiments show that annotation quality depends on both workflow depth and element-class grouping. Overall, careful workflow design can make LLM-based mobile UI annotation more reliable for UI understanding, dataset construction, and GUI agent development.