Help:Edit summary
Each edit on Wikidata has a short message called edit summary associated with it. When making edits to items, properties or lexems using Wikidata's regular web interface, the edit summary is automatically generated and cannot be customized unless the edit is a revert.
Custom edit summaries edit
Custom edit summaries can be specified using the EditSum user script or external tools such as QuickStatements. Developers using the Wikibase API can specify an edit summary with the summary parameter.