To assign quality levels to MS/MS library spectra, several community resources, including GNPS and MoNA, use a rating system. For example, on GNPS, library spectra are categorized based on the source of the MS/MS spectra. "Gold" spectra are derived from synthetic samples that have been characterized using mass spectrometry and an orthogonal analytical method, such as NMR or crystallography, and can only be contributed by privileged users; "silver" spectra are obtained from an isolated or lysate/crude sample with a scientific publication confirming the presence of the molecule in the sample; and "bronze" spectra are other experimental MS/MS spectra that provide evidence for putative or partial annotations. Finally, there are "in silico" spectra that have been produced using computational approaches. The latter are not selected by default when performing spectral library searching using GNPS, however, as we believe that such spectra should be used with extreme caution and generally only give insights into molecular families rather than specific identities. GNPS also allows users to update spectral library annotations if the original submission contained limited details (e.g. someone may have denoted the spectrum as a saccharide but further insights revealed that the specific molecule is azithromycin, or the original submission did not include the molecular structure which was subsequently added) or to correct previously misassigned library spectra. In these cases, the GNPS system always retains a complete record of the full annotation history. Additionally, GNPS allows users to rate the quality of MS/MS matches from spectral library searching using four star (correct), three star (likely correct, e.g. could also be isomers with similar fragmentation patterns), two star (unable to confirm the annotation due to limited information), and one star (incorrect) ratings. MoNA assigns a five-star quality rating to all spectra based on the amount of metadata that was provided (ionization mode, instrument model, collision energy, liquid chromatography details, etc.), and top rated MS/MS spectra and a leaderboard of their submitting users are advertised on the MoNA homepage. Additionally, users can rate spectra as being either "clean" or "noisy." These rating approaches allow users to manage expectations based on the evaluation of the library spectra so that they can make informed decisions based on the veracity of an MS/MS spectrum match, as well as provide feedback to help improve library annotations.