DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.
When in auto mode, the EnterPlanMode tool prompt is significantly reduced — it instructs the agent to skip planning in almost all cases and start implementing immediately, since auto mode users chose continuous execution. Plan mode is reserved only for explicit user requests or exceptional architectural ambiguity.
Evidence
Auto mode plan override (search for "Auto mode prioritizes continuous execution")
Strings lifted out of the shipped bundle, so the claim above can be checked against them.