"Of course they have useful tools for the garden."
Translation:Kompreneble ili havas utilajn ilojn por la ĝardeno.
The adjective would usually go before the noun in the English translation - "Useful tools for the garden" - regardless of where the adjective is in the Esperanto sentence. "Tools [that are] useful for the garden" would still be understood in English, and it's technically correct, but it's an unusual way of saying it. If you want to sound 100% natural then put the adjective first in this case.
Hope that helps :)