How to use "agent" in a sentence

We now have a secret agent, working within the government

And this is Frank Crawley, our agent.'

He told me what a good agent he was and how he loved Manderley.

once an agent, always an agent

"Once an agent, always an agent," Elliot said

Nevertheless, he was an intelligence agent a hell of a lot longer than he's been a judge, and I guess breeding tells

The Network had a deep-cover agent named Jacklin in the highest policymaking ranks of the Health bureaucracy

But I do know his agent's number