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 v2.1.301,
ImprovementsSection of the release
Unclear It is not clear in which sessions this limit is switched on.
What
A subagent is a helper agent that Claude starts to work on part of a task. Sending a subagent a message with SendMessage, or resuming one, now counts against a limit between two of your own messages.
When that limit is used up, or there is no room left, the request is refused. Claude sees a "Not sent" or "was not resumed" message saying the session's agents have launched, resumed and written as often as they may before you next write. When a subagent is resumed, the result now also includes a revivedAgentId next to resumedAgentId.
Why
This stops agents from messaging each other without end. You may see Claude stop and wait for you after a lot of agent activity, until you write again.
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 doubtIt is not clear in which sessions this limit is switched on.
