The phrase "agents were unable to" is correct and usable in written English.
It can be used to indicate that agents could not perform a specific action or task.
Example: "Despite their best efforts, the agents were unable to locate the missing documents."
Alternatives: "agents could not" or "agents were not able to".
Yet the investigation was closed after agents were unable to verify any suspicious ties.
The agents were unable to prevent the deaths of 12 students and one teacher.
Agents were unable to obtain any information more specifically identifying Zhang's purported contact, 'Charles,' " the complaint said.
Ten co-defendants were quickly rounded up by the Federal Bureau of Investigation, but agents were unable to find Mr. Tomasello.
Agents were unable to identify those visiting the site through the service's record so continuing to run the site became the only way of identifying offenders.
Charles A. Gaston, a telegrapher serving in the 11th Mississippi and detached as a scout, intercepted Union messages encrypted in Stager's code near Petersburg in the last year of the war, but Confederate agents were unable to break the code.
Without such assistance, control agents are unable to acquire the local knowledge necessary to locate and prosecute deviants.
Muqrin and three others died in a shootout at a Riyadh gas station, but a dragnet by thousands of Saudi police officers and other security agents was unable to find Johnson's remains.
Sometimes, though, over the course of a busy eight-hour shift, the slots need to be cleaned again, but the agents are unable to leave their booths to do it.
Players will argue that they have been harmed by the lockout — free agents are unable to sign and roster bonuses are not being paid — but most players will not lose their biggest paydays until the first week of the regular season.
For larger networks, instead, adding new random topics quickly removes polarization because locally the communication flows efficiently, but the positive effect is then limited by the fact that with few hub nodes in the network agents are unable to easily find new peers.
