I suppose you could consider them communists. The term gets thrown around very loosely these days. The Wikipedia article on communism lists Spartacus' revolt as an early example. I'm not sure why; the quote they rely on for evidence has almost nothing to do with communism. But if communism has become such a meaningless term, why not tag the Gracchi with it?

If you mean "communists" as in people who are worried in some way about the ownership of the means of production, you probably better not use that word for the Gracchi. Ti. Gracchus' proposal wasn't about nationalizing land; he wasn't even trying to take land owned by private citizens. If anything, he was trying to privatize ownership.

The Roman state held ownership of a bunch of land that in theory it rented out to raise money. Ti. Gracchus, faced with what he perceived to be masses of poor driven from their small farms by rich landowners (whether he was right about this is another question entirely) wanted to give that publicly owned land to individual poor people. He was literally privatizing the means of production.

The conflict with the wealthy that sometimes makes people suspect him of early communism came about because the wealthy had been renting that land, and over the years had come to treat it less like rented property and more like their own private property, and were not happy about being pushed off it. Ti. also stepped on the toes of Italian land owners because the survey commission he set up to manage the redistribution of Roman land was sloppy and ended up redistributing a lot of land the Roman state didn't own, including a lot of Italian land.

As for names or slogans, Cicero repeatedly grouped them with populares (who were not a political party, but rather a name for people of whatever political persuasion who preferred to pursue their policies through popular assemblies rather than the Senate, and how about that alliteration, hey?), and often says Ti. aspired to be King, which seems to have been a real charge his opponents placed against him. Both the Gracchi associated themselves with the Aventine, which itself has associations with plebeians and the god Liber. There is not, as far as I am aware, evidence of a slogan such as "Peace, Land, Bread."