This page and Wikidata Query Service/User Manual#MediaWiki API give examples using the following params:
gsrsearch, gsrlimit, gcmprop, gcmlimit
Where are they documented?
The page says "It is permissible to add input parameters not specified in the configuration, they will be passed to the service query. Please refer to the API documentation for the lists of parameters each service has". I searched in API:Query#Generators and can't find them there.
It would be very useful for SPARQL devs to have a full list of params listed on this page, maybe with links to their definitions in the MW API page.