After I finish cracking nuts with a hammer on Shabbos, can someone take the hammer from my hand and return it to my tool room? I saw that the Mishna Brura in the case of the knife of a Mohel permits another person to receive the knife and place it in a safe place.
It is permitted for somebody else to carry the hammer. This is not similar to the case of the milah knife, however, and the reason why this is permitted is that the hammer needs to be moved “for its space” (the person’s hand) so that no prohibition applies for a hammer.
In the case of the milah knife the reason why some authorities are lenient is because the knife is not mukzeh: When Shabbos came it is was required for the milah, and there is no muktzeh for “half a Shabbos” (see Shevet HaLevi 8:91).
This is not true of the hammer. However, the hammer is only muktzeh machmas melachah, and it is permitted to move it for using it or for its space. Here, we require its space (the hand of the person holding it) and to clear the hand it is permitted for somebody else to take it.