The phrase "tipped one hand" implies that someone has revealed their agenda or intentions, leaving themselves vulnerable or exposed. Antonyms for this phrase might include "guarded," "discreet," "secretive," or "reserved." These words suggest a withholding of information or an unwillingness to reveal one's true motives, indicating a sense of caution or self-protection. Other antonyms might include "deceptive," "manipulative," or "untrustworthy," which connote a deliberate attempt to mislead or take advantage of others. Ultimately, the opposite of "tipping one's hand" depends on the context and the implications of the action, but it generally involves some degree of secrecy or strategic restraint.