TONTO is a transfer system after LHO opens a 3-level preempt and partner overcalls 3NT. The term is an acronym for "Transfers Over 3 No Trump Overcalls."
A description of this convention was likely first published in the December 1995 issue of The Bridge World by Mr. Robert Stone.
The responses to the 3NT overcall are aimed at transferring the partnership into the desired trump suit. By utilizing transfer bids instead of direct bids, the partnership can try to ensure that the strong hand - i.e. the 3NT bidder - becomes declarer.
Additionally, there is a modest possibility that the partnership can identify a great trump fit and probe for a slam.
The basic transfer sequences are represented in the following tables. Additional details are necessary for discussion by a partnership.
.
Against a Minor Suit Preempt
|
West
3 /
|
|
North
3NT
|
|
East
Pass
|
|
South
?
|
| Response |
Meaning |
| 4 | Transfer to 4H. Partner can "super-accept" by bidding 4. |
| 4 | Transfer to 4S. Partner can "super-accept" by bidding 4 . |
| 4 | Transfer to 5 of the other minor. The meaning of the intermediary bids TBD by the partnership. |
Against a Major Suit Preempt
|
West
3/
|
|
North
3NT
|
|
East
Pass
|
|
South
?
|
| Response |
Meaning |
| 4 | Transfer to 4 of the other major. Partner can "super-accept" by bidding 4. |
| 4 | Transfer to 5. Partner can "super-accept" by bidding 4. |
| 4 | Transfer to 5. The meaning of the intermediary bids TBD by the partnership. |
