The Standard Representation Agreement ("SRA") between a player and an agent ("Contract Advisor") is filed with the NFL Players Association. A sample SRA can be found here (see Appendix D on page 37 of the document). More FAQs about being an NFL agent can be found on the NFL website.
Here's some "words of wisdom" from Auburn University to its athletes about the "Big Bad Agent Man (or Woman)."
The Contract with the Agent
The NFLPA Standard Representation Agreement is standard form contract players' sign with agents. It is a bare bones agreement that authorizes the agent to “represent, advise, counsel, and assist the player in negotiation, execution and enforcement of his playing contract(s) . . .”
What else does it do?
It should specify the services provided by the agent beyond contract negotiation. Agents may ask you to enter into agreements for other types of services: make sure those agreements are rolled into this agreement. Some services you may want handled by someone other than your agent (financial planning and accounting, and estate planning). Other services might be also handled by this agent (endorsements, career and post career counseling, marketing and insurance). It sets the term limit of the agreement: when the agent starts working for you, when he stops. It sets the amount the player compensates the agent (3% of player’s compensations for each season he plays—but you can negotiate a lesser amount). It sets how the player compensates the agent.
If you settle on the contingent method, do not allow the agent to take the full percentage up front. Fees should be paid on an annual percentage of the player’s earning—and only after he has actually earned the money. It sets the kinds and amounts of expenses for which the player will reimburse the agent (generally “reasonable and necessary” communication and travel expenses incurred “in connection with the negotiation” of the players contract. This is paragraph 6 on the agreement. You should ask your agent to remove this. It should also specify the expenses the agent is willing to pay: Preparation for combine and interviews, for example is something you should ask him to pay for. If on the other hand he promises to arrange combine/interview prepration, make sure you contract is clear on who pays. It may contain an exclusivity clause. This gives the agent the right to a percentage of all the player’s playing contracts and endorsements—even if he’s fired and another agent negotiates the contracts.
As you can see, schools are telling their players to let the rich-guy agent pay for everything -- this is one of the reasons that players who have as much chance as playing in the NFL as Pee-Wee Herman are asking for handouts from agents.