About [[MediaWiki:Spamdifftool-tool/en]]
If this is a name of a tool which shouldn't be translated, this message is useless.
The documentation is just plain wrong here. It can, should and has been translated already (i.e. the German translation is currently "Spam-Werkzeug", which means "Spam Tool", the French translation ("Outil Spam") also translates back to "Spam Tool" etc.). The proper name of the extension is SpamDiffTool.
For some context: the message in question is the page title — or rather, "HTML title"; that is, the text displayed on your browser's window/tab — of the Special:SpamDiffTool page. It isn't shown anywhere else. You might want to take a look at the extension's infopage on MediaWiki.org for a screenshot of the extension in action and more.