Stocks rallied after Federal Reserve Chair Janet Yellen on Tuesday reassured Wall Street that the central bank would continue its policy of providing monetary stimulus to bolster the economy, but Jim Grant—founder and editor of Grant's Interest Rate Observer—told CNBC that her testimony before Congress was lacking.
"She neglected to tell us that the Fed is continuing on this unprecedented exercise in price control," he said on "Closing Bell." "The Fed has, in its 100-year past, manipulated interest rates before, but never until now has it treated the stock market as if it were a lever of national public policy, which it is doing. The Fed has its thumb on the scales of our finances."
(Read more: Yellen defends Fed, saying these are 'unusual times')
Though Yellen is thought to be more "plainspoken" than her predecessor, Ben Bernanke, she failed to disclose that the central bank is manipulating interest rates and the dollar outright, Grant said.
Veteran trader Rick Santelli, who has long been skeptical of the Fed's stimulus program, seemed to hold a similar view.
"She gets an A because there's continuity, OK? Where I come from, continuity from a bad plan to continuing that same bad plan doesn't garner an A . I would give her an A if she didn't have continuity," Santelli said from the floor of the Chicago Board of Trade.
But reaction to the Monetary Policy Report, Yellen's first since she was confirmed as chair of the Federal Reserve on Jan. 6, was largely positive. Tuesday's rally marked the best four-session stretch for both the S&P 500 and the Nasdaq in more than a year.
(Read more: Yellen speaks; The market loves it)
"She really nailed it. She stuck the landing. That's why we were up so strong today," said Jon Najarian, an options trader and co-founder of optionsMONSTER.com.
Appearing on "Street Signs," body language expert Tanya Reiman remarked that Yellen has an "asymmetrical" or "downward" mouth, so people are going to be quick to judge her based on her perhaps inadvertent expressions.
"A lot of times when you see a mouth move in certain positions, my job is to tell you that meant contempt, that meant anger," Reiman said. "With her, you have to recognize that's one of her normal behaviors, so you can't judge her on that."
She noticed that Yellen crossed her arms and raised her eyebrows a few times, which means she may have felt insecure or under pressure.
"You're going to see points of anxiety leak out, but she was consistent for the most part," said Reiman, who has written two books on body language and communication. "I thought she did really well for the first time."
—By CNBC's Drew Sandholm. Follow him on Twitter @DrewSandholm.