LiteOdyssey: A Lightweight Reasoning AI Agent for Interpretable Rare-Disease Diagnosis

LiteOdyssey is a lightweight AI framework designed for rare-disease diagnosis that employs a reasoning language model guided by a diagnostic policy developed through human-AI collaboration. It achieved state-of-the-art performance on two benchmarks, with a Recall@1 of 59.3% across 1,243 cases, and 60.7% on the more challenging PhenoPacket subset, significantly outperforming the baseline model (GPT-5.4) without the use of fine-tuning or large retrieval databases. This framework highlights a shift towards more interpretable and deployable AI systems in the medical domain, particularly for ultra-rare diseases, by utilizing dynamic access to public biomedical tools.