Two different types of assay descriptors were evaluated: fingerprints and embedded assay descriptions. Fingerprints were created based on metadata available in ChEMBL and bag-of-words feature extraction. For the fingerprints based on metadata, properties were included if 100% of the property was defined and the property contained 40 or less unique categories (Table 3). This was the case for the following properties: relationship type, standard type, src id, confidence score, BioAssay Ontology (BAO) format, curated by, and assay type. For the bag-of-words featurization of the assay descriptions, stemming was applied and English stop words (from scikit learn) and assay specific stop words (see Figure 2) were removed. The maximum descriptor length was capped at 1024 bits. On average 7.5 bits (each representing a word) were present per description.