Existing rescoring tools mainly differ from each other by their use of distinct feature sets and prediction models. Some PSM rescoring tools use only a few features by default , while others use dozens to 100 features () . Additionally, some tools allow adjusting the number of features used. For example, MSBooster has an option to use correlated features or not, and inSPIRE allows manual feature inclusion and exclusion. Although a minor variation in feature sets that are used will likely have limited effect on the performance, in light of the diversity in the number and type of features used by various PSM rescoring tools, it is important to strategically select relevant and informative features.