When deferred tools are newly surfaced mid-session (via surfacedToolNames) without new schema lines being added, the system prompt now shows a plain "The following tools just became available and are ready to use" message, instead of the schema-loading instructions previously given for all newly added tools.
Newly surfaced deferred tools get their own announcement message
Tools that just became usable mid-session are announced as ready rather than told to load their schemas first.
You'll noticeTier: how much it should matter to you
2Useful: my rating, 1 to 5
2Signal: worth watching, 1 to 5
ToolsArea: what it touches
ImprovementsKind: in v2.1.257,
ImprovementsSection of the release