Others will know more, but my $0.02:
Two biggest things to consider in my book are-
1-commission level (make sure you are happy with what's agreed, the major change would be any higher-than-standard payment to the buyer's broker)
2-length of agreement. Don't know MA specifically, but in NY & CT many brokers try for 6mos or even 1yr. If you're comfortable with that length, good. If not, feel free to shorten it. If you do shorten it, make sure to review a couple weeks before the expiration date, that way if you want to extend the agreement you & your agent have plenty of time to do that smoothly
Most such agreements are pretty standard. Usually an awake-and-alert read through will do it, no particular need for a lawyer unless there is some special issue with your property imo. Some agreements list in detail what the agent/broker will do to market your home, others don't. If you have any specific requests/concerns (frequency of open houses, pre-screening of potential buyer, folks taking off/covering their shoes, marketing details, etc), discuss *before* signing the agreement. Remember the agreement is technically with the brokerage, not with the agent - again, if you have any questions/concerns best to discuss before signing.