Hi Rémi! Sorry that nobody has taken a look at this report yet and given feedback.

(In reply to Rémi Kaupp from comment #0)

On the French Wikipedia, we have added a "toolbox" for categories,
seen on [[:fr:MediaWiki:Categoryarticlecount]].

Following that link I get: Cette page a été supprimée (from 2008 already).

Looks like it redirects to https://fr.wikipedia.org/wiki/MediaWiki:Category-article-count now. Which displays

	Erreur d’expression : opérateur '''<''' inattendu.

for me.

(whoo, I didn’t notice this bug, although I did an action close to it.)

I guess the (1) of the initial report has been fixed a long time ago: iirc back to 2006 the messages category-files-count and category-subcat-counts didn’t exist.

The current error is only displayed on the MediaWiki: page since the Lua/template code behind is only working on category pages.

If I understand correctly the initial proposition, the idea is to create a message "MediaWiki:Category-toolbox" before or after the wikitext of the category to show some toolbox. In this case, it is simply adding an empty (by default) message system in some place in the category pages, but before or after the wikitext is a usability issue. Perhaps adding it in the top of the page would be better to allow a toolbox in float:right, since category pages usually have a few wikitext. Or adding two messages before and after the wikitext, I don’t know if the choice should be given.

See e.g. https://fr.wikipedia.org/wiki/Catégorie:Snowboard?uselang=qqx to see the structure of a category page with all system messages displayed (this category currently has the three types of pages: subcategories, pages, files).