Assistant District Attorney Charles Linehan accused Anna Gristina of making empty boasts - picked up by surveillance before her arrest - that she had connections in the FBI, New York Police Department and other law enforcement agencies who would tip her off when needed.
"We have no evidence to support any of these claims," Linehan said in state court. "(Gristina) ran a brothel for many years - that is all."
Judge Juan Merchan also scolded Gristina for drawing needless attention to herself, including bringing her young son Nicholas to court on Tuesday amid a throng of news cameras.
"I can't see the benefit of exposing him to this," he said.
Gristina and her lawyer left court without speaking to reporters.
The 45-year-old native of Scotland pleaded guilty to a single count of promoting prostitution, stemming from a July 2011 tryst that authorities say she arranged involving two women and an undercover officer posing as a client named Anthony.
The prostitution charge carried a possible sentence of 2 1/3 to seven years in prison. But the judge said he would give her only six months - an amount already covered by the time served before her release on bail in June.
The judge warned that a bigger problem for Gristina - a legal U.S. resident from the Scottish Highlands - is that she could be deported as a result of the conviction.
Sentencing was set for Nov. 20.
Gristina's lawyers had painted a picture of benign domesticity: They said their client lived on a 12-acre property in Monroe, about 50 miles north of New York City, and rescued animals and helped abandoned pet pigs find new homes. She also had said she was merely starting a dating service.
But prosecutors alleged she had secretly made millions of dollars during about 15 years of booking prostitutes for well-heeled clients. They said many of the trysts occurred at an apartment on Manhattan's Upper East Side.
Her lawyer, Norman Pattis, had sought to get the case dismissed by arguing that the district attorney's office "vindictively prosecuted" her because she wouldn't cooperate during an illegal interrogation.
In court papers, Gristina accused detectives of shrugging off her requests for a lawyer and telling her they'd let her go if she gave them information about five men - not named in her filings, but described as a financier, an international banker and a member of a politically connected family, among others.
The DA's office countered in their own papers that Gristina "has not produced a shred of evidence of actual vindictiveness."