You may come across well-meaning people who'll tell you that only scam artists posing as literary agents require contracts with authors before a book is sold. In fact, many (if not most) reputable agencies have standard contracts with their clients that spell out such terms as the scope of representation, the agent's commission, additional expenses, and the responsibilities of each party. An author-agent contract is more the rule than the exception these days.

Agent-author agreements cover virtually all aspects of your business relationship. Here are four of the most critical areas:

• Scope: Often, the agent is granted exclusive rights to represent all your book-length work, in all formats and media, worldwide. Once in a while, an agent will contract to represent just your current book project, but this is unusual. It's also quite rare for an agent to represent shorter work, such as short stories, magazine articles, and individual poems; payments for these works are much lower than for book sales, and the agent's time isn't worth the 15 percent commission.

• Duration: Most contracts have a term limit, often ranging from one to two years. Many initial contracts cannot be terminated for a set period — six or twelve months, for example — but have a termination clause that kicks in after that initial period. A typical termination clause allows either party to pull out of the agreement with thirty to ninety days' notice. The agreement should also specify what happens if you want to take your book project to another agent.

• Commission: The agreement will spell out what the agent is entitled to receive as a commission on sales — usually 15 percent for domestic sales and a higher percentage for foreign sales.

• Handling of payments: In a typical agent-author agreement, the agent is empowered to receive all the author's advances and royalties from the publisher, take her commission from those proceeds, and send the remainder to the author.

It's important to take this seriously. You should always have a reasonable time to review and sign the contract.

Be wary of any contract with an agency that requires you to pay up-front fees. Even reputable agents who pass mailing, telephone, and other business costs on to their clients won't charge those fees until after a book is sold. An agent who wants money up front is likely making his living from those fees, not from selling authors' manuscripts to publishers.