{"version":"2.1.321","anchor":"mcp-task-cancellation-killed-agent-delivery-dropped-auto-b","canonical_anchor":"mcp-task-cancellation-killed-agent-delivery-dropped-auto-b","heading":"Messages to a subagent that was stopped meanwhile are dropped","tier":"notice","area":"Agents","scope":"individual","heads_up":false,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.321\/e\/mcp-task-cancellation-killed-agent-delivery-dropped-auto-b","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.321","markdown":"### Messages to a subagent that was stopped meanwhile are dropped\n\nA message for a subagent that was stopped in the meantime is now dropped with an error, and MCP tools wait longer before moving to the background\n\n**What**\n\nA subagent is a helper that Claude starts to work on part of a task. If a message is on its way to a subagent and the subagent is stopped in the meantime, Claude Code now drops the message with an error saying it was stopped meanwhile. Before, this was refused only when you had stopped the agent yourself.\n\nMCP tools, which are outside tools connected through the Model Context Protocol, can be moved to the background when they run long. That move now also waits while something holds it back.\n\n**Why**\n\nIt avoids reviving a subagent that was stopped just as a message reached it.\n\n- Area: Agents\n- Tier: You'll notice\n- Useful: 1\/5\n- Signal: 1\/5\n- Scope: individual\n- Heads-up: no"}