This paper explores the application of Swarm-Structured Multi-Agent Systems (MAS) to establish medical necessity, a process that involves a systematic review of patient-specific medical structured and unstructured data against clinical guidelines. We addressed this complex task by decomposing it into smaller, more manageable sub-tasks. Each sub-task is handled by a specialized AI agent. We conduct a systematic study of the impact of various prompting strategies on these agents and benchmark different Large Language Models (LLMs) to determine their accuracy in completing these tasks. Additionally, we investigate how these agents can provide explainability, thereby enhancing trust and transparency within the system.