iserith
Magic Wordsmith
Not everything needs to be DM adjudicated, some things are clearly spelled out.
All actions are adjudicated by the DM. See "How to Play," Basic Rules, page 3. When the DM determines that what the player described he or she wanted to do has an uncertain outcome, the DM invokes mechanics to help determine a result.
"This pattern holds whether the adventurers are cautiously exploring a ruin, talking to a devious prince, or locked in mortal combat against a mighty dragon."
There should be no rules expectation on the part of a player that they get to make a check. (They might expect a given DM will rule a particular way, however, based on experience at that DM's table.) Further, asking to make a check is asking for a chance to fail when the DM may simply rule in your favor and grant auto-success based on his or her assessment of your goal and approach relative to the context of the situation.