Try this, taken directly off
the wiki:
void SetEntityPlayerInteractCallback(string& asName, string& asCallback, bool abRemoveOnInteraction);
Calls a function when the player interacts with a certain entity.
Callback syntax: void MyFunc(string &in entity)
asName - internal name
asCallback - function to call
abRemoveOnInteraction - determines whether the callback should be removed when the player interacts with the entity
For you, this would mean you should use:
SetEntityPlayerInteractCallback("crowbar_1", "MonsterActivate1", true);
Also, make sure you change the inputs for your MonsterActivate1 function to match the callback syntax.