Benjamin Franklin paraphrase:
We gave Mars an atmosphere, if Mars can keep it.
I would question Mars’ ability to hold a stable earthlike atmosphere. Its size and mass make it the reason for what it is right now.
There is nothing insufficient about Mars' mass (size is irrelevant). Early Mars had a LOT of carbon dioxide. The weight of that gas alone was enough to provide Mars with an atmospheric pressure equal to that on today's Earth. Even Saturn's moon Titan has a substantial atmosphere (Titan is under the protection of Saturn's magnetosphere). The problem is, if you let the solar wind get to your atmosphere, you're going to lose it. Even Earth will lose its atmosphere it our molten core quits spinning.