Two knights is the least challenging minor piece combination against single rook in the endgame.
TRADE: two knights for a rook
As has been already stated position is the determining factor however, if you look at it from number of pieces, 2 vs 1 attacking or defending is a definate advantage.
More pieces are usually an advantage over fewer, since they are more difficult to capture and can be more places performing different tasks at the same time. Having a single, powerful, cumbersome piece can be a disadvantage, since it can only do one thing at a time. For example, if you could have three bishops or knights for a queen, wouldn't you consider that an advantage? Add to this the fact that the two knights are worth a point less than the rook, and the advantage of having the former over the latter seems decisive.
The minor pieces need proper coordination to outsmart the rook. The rook is not prone to this achilles heel.
Here is the rule:
When considering two knights or a rook, look at the position and ask yourself, “Is the position open enough for the rook?” There, the answer should be clear. One note: Never depend on points to guide you in chess. Even if two knights are “worth” six points, the position is always the real deciding factor.
Yep. Open game you want those rooks. Generally. But as usual it depends on the position.
2 knights working together are far more powerful than one single Rook. Watching 2 knights dance around a rook causing chaos poor little Rook can only move in horizontal and vertical lines knights jump all over the place. Once they both get into the center of the board good luck Little Rook dealing with that.
I concede that Two Knights > R but the horse duo offer the least resistance to the tower under otherwise equal circumstances.
In practice, one pawn is usually sufficient for the rook to play on equal terms in the endgame. Against bishop and knight one to two pawns. And against bishop pair the rook needs minimum 2 pawns >
NN v RP + a smidgen.
NB v RP + around half a pawn to three quarters.
BB v RPP + about half a pawn.
In any case, it all depends on how active the rook is in relation to the minor pieces and the pawn formation.
Actually that trade is good. Analyze it with a computer.