Details emerged Friday from the U.S.’s first-stage trade deal with China, which marked a milestone in President Trump’s initiative to rebalance trade with Beijing but left questions over how far it goes to level the playing field for U.S. businesses.

The limited agreement, capping months of sometimes-testy negotiations, calls for China to purchase more products from American farmers and other exports, U.S. officials said. In return, the U.S. put the brakes on new tariffs set to take effect Sunday and agreed to reduce some existing levies. Both sides termed it a “phase one” deal and said negotiations would continue on remaining issues.

Mr. Trump called the deal “phenomenal” and told reporters in the Oval Office that the U.S. would continue to use the remaining tariffs as leverage in future negotiations with China.

“I say affectionately that the farmers are going to have to go out and buy much larger tractors because it means a lot of business, a tremendous amount of business,” Mr. Trump said.

But doubts remained, with some critics claiming the deal amounted to little more than China agreeing to step up U.S. farm purchases and not make the kind of long-term economic changes that U.S. officials have said are needed to level the playing field for businesses.