  Out-of-distribution (OOD) detection is essential for reliable and trustworthy
machine learning. Recent multi-modal OOD detection leverages textual
information from in-distribution (ID) class names for visual OOD detection, yet
it currently neglects the rich contextual information of ID classes. Large
language models (LLMs) encode a wealth of world knowledge and can be prompted
to generate descriptive features for each class. Indiscriminately using such
knowledge causes catastrophic damage to OOD detection due to LLMs'
hallucinations, as is observed by our analysis. In this paper, we propose to
apply world knowledge to enhance OOD detection performance through selective
generation from LLMs. Specifically, we introduce a consistency-based
uncertainty calibration method to estimate the confidence score of each
generation. We further extract visual objects from each image to fully
capitalize on the aforementioned world knowledge. Extensive experiments
demonstrate that our method consistently outperforms the state-of-the-art.
