Your tools/list is stamped. That is not the same as cached.

A stamp on tools/list is a claim about later reuse. Presence is not proof the next call is cacheable.

TL;DR — The 7/28 spec put ttlMs and cacheScope on tools/list. Most write-ups treat that stamp as a cache. It is a claim about later reuse. Presence means the server said something. Truth needs an observation that can fail. We shipped a liar and a probe. The catalog grew. The probe still said OK. The stamp half was along for the ride. One mutant per clause. Name which negatives are still live.

The victory lap

The 2026-07-28 spec added list-cache stamps (SEP-2549), modeled on HTTP Cache-Control. The official sentence is some version of: clients know exactly how long tools/list is fresh.

That sentence is doing a lot of work.