MediaWiki:Apihelp-query+readinglists-extended-description/en

This module has four modes of operation. With the $1list parameter, it returns information about the specified list. With the $1changedsince parameter, it returns all lists of the current user which have been changed since the given date. (This is meant for device sync and, unlike the other modes, includes deleted lists. Only changes to list metadata are considered, not changes to list items.) With the $1project and $1title parameters, it returns all lists that include that page. Without any of those parameters, it returns all lists.