You'll noticeTier: how much it should matter to you
3Useful: my rating, 1 to 5
3Signal: worth watching, 1 to 5
MCPArea: what it touches
ImprovementsKind: in v2.1.251,
ImprovementsSection of the release
What
MCP tool invocations dispatched over the SDK control channel now run with subagent spawning disabled, so a tool call cannot start a Task while it is running.
Details
Unconditional on this path.
Evidence
disallowTasks: !0
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
