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Which parts of a character's plan should be revealed beforehand?

Two characters (one is a PoV character) come up with a plan to break a third out of prison. They succeed, with only minor complications.

If I describe too many details of their plan beforehand, it feels like I'm telling the same story twice. If I don't include enough, it looks like they're making it up as they go along.

What would be a good way to tell which parts of their plan should be described in detail before the actual breakout?