@craw_advantage There is what you are required to do in accordance with the rules and there is what you consider ethical or moral or whatever. Since this is becoming a more in depth conversation, here is the relevant text.
"There are four categories of information: status, free, derived and private.Status information is information that must be announced upon change and physically tracked by the affected player. Methods for tracking must be visible to both players during the match. A shared method is acceptable as long as all players in the match have access to it. At Competitive and Professional REL, methods that can easily be accidentally changed (such as dice) may not be used. Status information consists of: Life totals. Counters a player has attached to them. Continuous effects with no defined expiration within the game that apply to that player, such as Monarch or City’s Blessing
Free information consists of: Details of current game actions and past game actions that still affect the game state. The name of any visible object. The number type of any counter that isn’t defined as status information. The state (whether it’s tapped, attached to another permanent, face down, etc.) and current zone of any object or player. The game score of the current match. The contents of each player’s mana pool. The current step and/or phase and which player(s) are active.
Example: If a player asks his or her opponent for his current life total, that player is required to respond truthfully and directly. Answers like, “You can figure it out” or “Twenty” when the player is actually at seventeen life are unacceptable.
These types of information need to be immediately pointed out when the change occurs.
A very common method of tracking life or counters on a player is with pencil/paper.
Free information is information to which all players are entitled access without contamination or omissions made by their opponents. If a player is ever unable or unwilling to provide free information to an opponent that has requested it, he or she should call a judge and explain the situation.
A player always has to give all free information to their opponent accurately upon request. If that is not possible they should call a judge to help clear up the communication. If a player unintentionally misrepresents free information at Competitive Rules Enforcement Level, it may result in a Communication Policy Violation.Derived information is information to which all players are entitled access, but opponents are not obliged to assist in determining and may require some skill or calculation to determine. Derived information consists of: The number of any type of objects present in any game zone that are not defined as free information. All characteristics of objects in public zones that are not defined as free or status information. Game Rules, Tournament Policy, Oracle content and any other official information pertaining to the current tournament. Cards are considered to have their Oracle text printed on them.
While a player is not obliged to assist his opponent with the Game Rules, Tournament Policy, Oracle text, or any other official information pertaining to the current tournament, a player may ask a judge for any of that information during a match. For example, if a player asks his opponent what a card does, for example, a player does not have to give all of the information about the card. His opponent may say that Vampire Nighthawk is a flying 2/3 creature and omit that it has Deathtouch and Lifelink.Private information is information to which players have access only if they are able to determine it from the current visual game state or their own record of previous game actions. Any information that is not free or derived is automatically private information.
Private information is the catchall category for everything that is not free or derived information. For example, the contents of hidden zones (i.e., library and hand) and the identity of face-down cards in public zones are considered private information. Players are allowed to give their opponents false information about the contents of a hidden zone. For example, if a player casts Slaughter Games and names Scapeshift, his opponent may say that he or she only has three copies of Scapeshift in his or her library, even if it actually contains four.
The following rules govern player communication:Players must answer all questions asked of them by a judge completely and honestly, regardless of the type of information requested. Players may request to do so away from the match. Players may not represent derived or free information incorrectly. Players must answer completely and honestly any specific questions pertaining to free information. At Regular Rules Enforcement Level, all derived information is instead considered free."
So again, at competitive REL, which is most (all?) Vintage events I have been at, there is no obligation to assist the opponent with derived information, or to call a judge for them. If players want to go above and beyond to assist an opponent, then there is certainly nothing prohibiting them from doing so.