When should you use illustration notes in a picture book manuscript?

As a children’s agent and picture book author, I’m a fan of art notes only when they are integral to the story. So if it doesn’t matter what color the protagonist’s dress is, or what’s in the background, etc., then I would always leave that up to the illustrator.

Let’s say you have something like:

And the bear picked up the hat.

SPLAT!

Oh well.

Then I think an art note might be warranted, because anything could have happened between the “SPLAT!” and “Oh well,” and presumably the thing that did happen is something that is pushing the plot forward. (In other words, it should matter exactly what happened during the SPLAT!, and so it’s likely that that is a place where you might need an art note.)

So you might do something like this:

And the bear picked up the hat.

SPLAT! (illo: top hat full of watermelons rips and fruit crashes to the ground)

Oh well. (illo: bear is upset)

Or maybe this story goes like this:

And the bear picked up the hat.

SPLAT! (illo: bucket of paint falls from scaffolding on bear’s new hat)

Oh well. (illo: bear smiles and puts on colorful hat)

Same exact text, but two very different stories when you give us art notes on the visual!