These may not be eggs, but cocoons of a tiny parasitic wasp.. I'll see if I can find which species.

In the image shown they do have more of the appearance of a cocoon than an egg. I'm guessing Alexis might be thinking of one of the parasitic wasps like braconid wasps, but having never seen their cocoons on anything other than the bodies of hornworms, it would surprise me to see them on leaves.....and it probably shouldn't. There's at least 17.000 known/described species of braconid wasps so it is likely that some of them do lay eggs on things other than hornworms. Your eggs do look almost identical to the brachonid cocoons I see on hornworms. There would be other options but Alexis' answer seems like the most likely one at this point.

Other pests that lay eggs on tomato leaves include brown stink bugs, green stink bugs, southern green stink bugs, and leaffooted bugs.Perhaps whiteflies do, though I seldom see whiteflies so am not very familiar with their eggs. Most of the stink bug type eggs are shaped like little barrels, although the barrel shape is not always apparent the first day the eggs are laid. It quickly becomes apparent later as does a change in the egg color. Most caterpillars that would lay eggs on tomato plants lay them singly and spaced out, not in clusters so I don't think you have hornworm eggs or any other sort of caterpillar eggs in that photo. Again, that is based on what I see. I know some gardeners insist that tomato fruitworms (generally believed to lay single eggs) lay eggs in clusters on their plants, so I'm not going to say it never happens.

When I see an egg or cluster of eggs I don't recognize and I care enough to try to figure out what it is, I pull the leaf, put it in a jar or ziplock bag and watch to see what develops. Sometimes the results can be surprising. When I've done this, 95% of the time, if not more, the creature that emerges from the eggs is a bad guy. Because of this, when I find eggs on a tomato plant, unless they obviously are ladybug eggs or spined soldier bug eggs, I automatically remove and destroy them.

I thought they also looked like the cocoons of a parasitic wasp but was surprised to see them there. I looked real close to see if maybe they had already consumed their food source and maybe a bit of carcass lay underneath, but I couldn't see anything.

Let me know Alexis if you find something out. I definitely don't want to destroy them if they are indeed my helpers.