No. Despite the name, buy-sell agreements have little to do with buying and selling companies. Instead, they are binding contracts between co-owners that control when owners can sell their interest, who can buy an owner's interest, and what price will be paid. These agreements come into play when an owner retires, goes bankrupt, becomes disabled, gets divorced, or dies -- in other words, a buy-sell agreement is a sort of prenuptial agreement between business co-owners. Mainly these agreements guide buyouts between the owners themselves; that's why we like to call them buyout agreements.
If you need legal advice for your business, talk to a lawyer.