Mike Schur, the co-creator of “Parks and Recreation” and “Brooklyn Nine-Nine,” tweeted at the end of talks: “WGA Members: What happens now? We stick together.” (Mr. Schur was one of the participants in the negotiations.)

What does an agent do, anyway?

The main job for writers’ representatives is to help the writers find employment and negotiate the highest possible compensation on their behalf. By law, agents must act in the best financial interest of their clients. They must also inform them of any possible conflicts of interest in a given deal.

There are all kinds of agents. The ideal version is a fierce advocate who may also act as an occupational therapist. At the other end of the spectrum is the one who doesn’t call you back. These days, the writers say, even the most assiduous agents can work against their clients’ interests, because the system itself is broken.

Can’t a lawyer or manager do the same things an agent does?

On this, the writers and agents strongly disagree.

The W.G.A. unions say that they are the writers’ exclusive bargaining representatives. As such, they can delegate who gets to negotiate on behalf of their members, and they have not hesitated to signal to managers and lawyers that they may effectively take on the duties of agents on the writers’ behalf.

But Latham & Watkins, the law firm working for the agents, sent a letter to the W.G.A. on Friday saying that, if managers or lawyers function as agents, they would be breaking the law. The firm pointed to the California Talent Agency Act and New York’s General Business law. No one may assume agenting duties without having an agent’s license, Latham & Watkins said in the letter, which went on to threaten that the agents would “take appropriate action as needed, against any person engaged in unfair competition.”

The writers countered that, with the legal letter, the agents were “attempting to intimidate attorneys and managers to stop them from performing work they routinely do.”