TDA Rule 35:
35. Pot Size
Players are entitled to be informed of the pot size in pot-limit games only. Dealers will not count the pot in limit and no-limit games.
I can make the argument that once a player says or indicates "all in", those chips are in the pot. That said, I personally believe that any player, yet to act subsequent to an "all in", has the right to know the exact amount of that wager, provided the request is made
"in turn".
For example, there is at least one visually impaired player on the tournament circuit (at least there used to be). Is this person not entitled to know the amount being wagered. While he was assisted, if I remember correctly his assistant was strictly limited to telling him his hole cards and the cards on the board. I could easily be wrong, but I don't think his assistant was allowed to give him information as to bet size.
My ruling would be that the player which the action is on, has the right to know the size of the bet and if the betting player will not state the amount of the wager, then the dealer has the obligation to do so. For example, I know of several places that use black chips, purple chips and dark blue chips. Personally, I have a difficult time telling the difference, so I have to rely on either the player or the dealer. That said, there has to be some 'reasonableness' in these requests. I have no problem rejecting the request if the chip stack is totally clear or if the player is abusing this request, etc.
Hope this helps.