bd016f45_Manual_Hooks___MediaWiki__Description
[Version] 1.2101.21.0 [Hook] SpecialSearchResultsPrepend [Called From] SpecialSearch.php [Description] 
Called immediately before returning HTML on the search results page. Useful for including an external search provider. To disable the output of MediaWiki search output, return false.
Manual:Hooks - MediaWiki
Description