Or actually, let me revise that a bit: what the card does isn't quite the instructions you follow when you play the card, but perhaps it's actually the sequence of game moves players take as a result of following instructions upon playing a card.
And if I play a Steward and choose +$2, what Steward did was (1) caused me to make a choice and (2) gave me $2.
I don't think your distinction is necessary or relevant. If you play Steward and choose +Cards, "the instructions you
follow when you play the card" are +Cards. Even though, with cards that have choices, you don't always follow
all the card's instructions, all the instructions you
do follow are the card's instructions. So again, "what the card does", in any particular case, are "the card's instructions" even though they might not be the totality of the card's instructions.* That doesn't hold with a Way: If you say that the card "does" the Way's instructions, that means that the card "does" instructions that are not the card's instructions (which doesn't seem to mean anything).
"what a card does" is the instructions you follow when you play the card, which may or may not be the instructions actually printed on the card (i.e., the card's instructions).
That definition for "what a card does" includes Adventures tokens etc.
I realize that
"makes you change what instructions you follow when you play the card" is not accurate enough to convey the meaning, because of our disagreement. The problems is, as I've said many times, that "when you play the card", you also follow the instructions of Adventures tokens, Kiln and even Royal Carriage. So all those also change what instructions you follow when you play the card (and are not the card's instructions). But what I meant of course was that Ways "make you follow another set of instructions instead of the card's
on-play instructions". I think we agree on this?
So your definition should read:
"what a card does" is the on-play instructions you follow when you play the card.But this can never include instructions not printed on the card.
If I play Harbor Village and then Steward, choosing +$2, I get +$1 from Harbor Village because giving me coin is something the Steward did. If I play Harbor Village and then Steward, choosing +Cards, I get no coin from Harbor Village because Steward didn't give me any coin (even though +$2 is apparently part of Steward's instructions). And if I play Harbor Village and then Smithy, choosing to play Smithy according to the Way of the Sheep, Harbor Village gives me +$1 because giving me coin is something the Smithy did.
As explained, you get +Cards or +$ from following Stewart's on-play instructions, that's why Stewart "does that". Sometimes following Stewart's on-play instructions can yield +$, sometimes not; i.e. sometimes Stewart "does" +$, sometimes not. Playing Smithy with Way of the Sheep makes you
not follow Smithy's on-play instructions, i.e. Smithy "does" nothing.
I think your confusion comes from thinking that it's meaningful to say that a card "does something" that somehow is not the same as you following its instructions. That's why I have asked you
to explain this.* Actually you could also say that you do follow the card's instructions in their totality, since it's part of Steward's instructions to choose to get +$2 or to not get +$2. Non-mandatory instructions are completed in full whether you choose them or not, and you have followed the instructions fully as long as you made one of the valid choices and resolved it.