Full-Body AI Agent: A Perspective on Multi-Scale Collaborative AI for Systemic Biology and Precision Medicine

Artificial intelligence (AI) is increasingly applied to biomedical research, but most current systems remain limited to specific tasks, data types, or biological scales. This makes it difficult to connect molecular alterations, organelle dysfunction, cellular behavior, tissue remodeling, organ physiology, systemic regulation, and whole-body phenotypes into coherent biological reasoning. In this Perspective, we propose the Full-Body AI Agent as a hypothetical multi-agent framework and conceptual blueprint for future systemic biology and precision medicine, rather than a fully implemented software platform. This framework envisions a supervisory Full-Body AI Agent coordinating seven biological-level agents, namely Molecule, Organelle, Cell, Tissue, Organ, Organ System, and Body System AI Agents, to standardize biomedical data, decompose cross-scale questions, assign level-specific tasks, and integrate outputs through iterative feedback. We further outline the data commons, harmonization mechanisms, uncertainty handling, arbitration strategies, and traceability safeguards required for biologically grounded cross-scale reasoning. Two hypothetical scenarios, metastasis analysis and drug development, illustrate how this framework could organize multilevel evidence from molecular changes to systemic phenotypes and therapeutic responses. This Perspective aims to clarify the conceptual basis of full-body AI and provide a foundation for transparent, physiology-constrained, cross-scale AI systems in disease analysis, therapeutic evaluation, and personalized medicine.