De vs Des
How come it’s DE petits outils and not DES petits outils
According to Monique L'Huillier in "Advanced French Grammar", des becomes d' or de when the noun is preceded by an adjective.
Thus it would be 'des outils' but 'de petits outils'.
In English, one would say 'an orange' but 'a small orange', so the presence of an adjective affects the choice of article there, too.