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.
The deferred tools announcement text has been simplified from lengthy explanations to concise notices: "Deferred tools appear by name in <system-reminder> messages" or "Deferred tools appear by name in <available-deferred-tools> messages."
Evidence
Updated deferred tools text (search for "Deferred tools appear by name")
Strings lifted out of the shipped bundle, so the claim above can be checked against them.