It was an overwhelming up-down -- both from the way Steve was (so easily) lifting him with one arm, and the way he was stroking him and there was zero denying how much he loved it. Hell, there was zero denying how much Steve loved it. Not with the noises he was making, or anything else.
An urging simply wasn't required -- Tony had been there already -- but the timing was good. Great even. He came somewhere between sinking all the way down on his cock and an upstroke of Steve's hand on his own. They always strived for good sex, and it'd yet to disappoint, but some times were certainly better than others and this one was one for the record books if Tony absolutely blanking as he made an absolute mess of his own chest and Steve's hand had any say in the matter. It was beyond seeing stars. Vision was for chumps. This was all of the senses getting everything he'd asked for and more. It was perfect.