The current message is dangerous. It explains that it's for *experimenting* and that this is a *sandbox*. As such I expected it to only simulate performing actions.
I assume that making it simulate actions would be difficult, so I am instead requesting that it clearly state that actions that modify the wiki, will in fact modify it.
Something similar to what the English language Wikipedia uses  would be good.
'Note that API actions that modify Wikipedia will in fact modify Wikipedia when used from this sandbox. For example, using the "edit" action will edit the specified page.'