Under the hood
Deferred MCP tools announced by a previous worker are re-seeded from the transcript during query preparation.
New machinery re-seeds tool references for MCP tools that a prior worker process had already announced with defer_loading: true, by scanning transcript attachments of type deferred_tools_delta. It logs Dynamic tool loading: seeded ${n} tool reference(s) to ${k} deferred tool(s) the previous process sent and is wired into the query-preparation path, guarded by Oe.readsTranscriptRecord.
Names in the bundledefer_loading
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
Confirmed since
Anthropic's documentation has since written up defer_loading, on Batches.
- `defer_loading: optional boolean or null`api/messages/batches see the edit
Gate removed from the code
v2.1.267 removed the tengu_plucky_orchard gate from the code while it was still reading on for the account this site reads.
The code path no longer asks a flag before it runs.
One source agreesOne thing we can check says the same as this entry.
Anthropic's documentation agrees
Anthropic's documentation has since written up defer_loading, on Batches.