You'll noticeTier: how much it should matter to you
3Useful: my rating, 1 to 5
3Signal: worth watching, 1 to 5
SubagentsArea: what it touches
ImprovementsKind: in v2.1.299,
ImprovementsSection of the release
Unclear Which mode or setting this applies under is not stated.
What
A subagent is a helper agent that Claude starts to handle part of a task. The instructions agents receive have changed: they are now told to deliver their final report through a dedicated call, because plain text written at the end is not delivered.
The SendMessage tool, which agents use to message each other, also has new refusals. One of them is "Not sent. This session has no saved settings for agent". The tool's own description is unchanged in this release.
Why
This changes how agents hand results to each other. A report left as plain text at the end of an agent's work no longer reaches anyone.
How sure we are
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubtWhich mode or setting this applies under is not stated.
Anthropic's release notes agreeFixed SendMessage not finding a subagent by name after the CLI restarted and resumed the session (names given before the last compaction…
