What
A subagent is a helper Claude starts to work on part of a job. When a subagent runs in the foreground and creates or updates tasks on the task list, its result can now include a taskCalls field.
taskCallslists the subagent's task-list calls in order, with each call's tool, input and result text.- It is optional in the Agent tool's output, and is marked internal: not a stable field for other programs to rely on.
- It is capped at 16384 bytes. A larger result is dropped, with the reason
over_size_limit. - Whether calls are recorded is decided by the server-controlled switch
tengu_bright_kettle, with a fallback of off. The same check used to readtengu_hushed_wren. Because the name changed, any server-side value set for the old name no longer applies. - The switch also widens which tool names are counted as task-list calls.
Readings this site took before this release found tengu_bright_kettle off for its own account and for an anonymous one. No reading has been taken under this release.
Why
Task-list changes a subagent makes appear in no other part of the transcript, so this lets the main conversation see them. Because the switch was renamed, whoever had the feature under the old name may lose or gain it.