CNBC's Jim Cramer breaks down how investors should play the stock market as both a Fed announcement on interest rates Wednesday and Trump's tariff increase on Chinese imports loom. The "Mad Money" host breaks down why certain department stores are doomed, outside of the Amazon effect. Later in the show he doubles down on his bet that AT&T is investible, despite an analyst's recent sell call on the stock.

CNBC's Jim Cramer said Monday that stocks will jump if the Federal Reserve puts a lid on interest rate increases and the Trump administration does not back away from hiking tariffs on China.

Wall Street is anticipating Fed Chair Jerome Powell's comments Wednesday on monetary policy and President Donald Trump's final decision on a planned Dec. 15 tariff hike on items, including laptops and smartphones, assembled in China.

"If Powell says nothing about tightening and the president holds off on the next round of tariffs, this market will soar," the "Mad Money" host said. "But if they both go the other way, stocks are going to sell off, and you have to be ready to buy them into weakness caused by the perennial pessimists who dominate, endlessly, our airwaves."

Department stores "have never felt more irrelevant," Cramer said.

Consumers are finding it easier to shop for better prices from their cellphones, and retailers such as and are finding it harder to staff their stores, especially during this holiday shopping season, the host said.

"Now these troubled retailers can't afford to offer the same level of customer service they used to. Sometimes they have long lines, sloppy aisles, empty registers," he said. "These are all common complaints about most of the mall-based department stores that I read online. They can't afford to be run efficiently."

AT&T shares are worth leaving in the portfolio, despite the sell recommendation recently issued by one industry analyst, Cramer said.

He doubled down on his belief that there is substantial upside in the stock price, thanks to activist investor Elliott Management's position in the teleco giant.

"If AT&T were trading in the $40s or even the mid-$50s, where Elliott believes it can go if the company hits its long-term targets, then the stock would be a sell here," he said. "But at $38, AT&T's already trading like those estimates are unlikely. And, hey, if management can deliver, I see this stock going much, much higher."

In Cramer's lightning round, the "Mad Money" host zips through his thoughts about callers' favorite stock picks of the day.

Kellogg Company: "Can I just go with high-quality here? We interviewed [ CEO] Jim Quincey this morning ... even better is — PEP, that's the one I want you in."

Teladoc: "Let's wait and see if the head and shoulders pattern continues. I'm enough of a chartist to care about that ... but I do like the stock."

Wynn Resorts: "I got to wait to see what they do with trade. No sense to go out in front of the trade deal, no sense."

Disclosure: Cramer's charitable trust owns shares of Pepsi.