US President Donald Trump (2nd R) and North Korea's leader Kim Jong Un (2nd L) sign documents as US Secretary of State Mike Pompeo (R) and the North Korean leader's sister Kim Yo Jong (L) look on at a signing ceremony during their historic US-North Korea summit, at the Capella Hotel on Sentosa island in Singapore on June 12, 2018.

With the ink barely dry, the much-anticipated agreement signed by President Donald Trump and North Korean leader Kim Jong Un quickly drew hard-hitting criticism for being short on specifics, especially on what denuclearization really means.

A photo of the document, which Trump deemed "very comprehensive," revealed that North Korea will work toward "complete denuclearization," among other points that the two leaders agreed on. But many experts expressed dismay and disappointment at the accord.

Andrew Gilholm, director of North Asia analysis at Control Risks, called the statement "brief and vague" and said it lacked any detail or new commitments.

"It is likely to be criticized by many observers who object to Trump dealing with Kim without tangible North Korean commitments to real, rapid denuclearization, although such commitments were never a realistic expectation," he told CNBC via email.

Parag Khanna, a senior research fellow at the Lee Kuan Yew School of Public Policy in Singapore, told CNBC he didn't think the declaration contained an actual definition of denuclearization, suggesting a convergence between the two sides. Even before the agreement was signed, most experts believed that denuclearization meant different things to both leaders. To Trump, this would mean no nuclear weapons in North Korea, while for Kim, it's about having no U.S. troops in South Korea.

Andrei Lankov, a professor at Kookmin University in Seoul, said the agreement has "zero practical value."

"The U.S. could have extracted serious concessions, but it was not done. N.Korea will be emboldened and the U.S. got nothing," he tweeted.

Bruce Klingner, a senior research fellow at think tank Heritage Foundation, called it "very disappointing."