Those are generally reckoned to be the corvids. Crows, Jays, Magpies, Choughs, Ravens etc. We know that crows can count (they can recognise a box with food in it by the number of spots on the top, regardless of size or disposition of the spots).
We know, by observation, that they can work out how to use simple tools.
They have been observed dropping pebbles in water jars to raise the level of water to a drinkable level.
Not such bird brains after all.