Cancel a running worker Use when native Bash hooks (via Claude Code\
AI agents call hooks_worker-cancel to permanently remove resources in Claude Flow — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
Cancelling a running worker is an irreversible action: any in-progress computation, queued tasks, or partial results are discarded and cannot be recovered. This matches the Destructive category (irreversible termination of an active process). Severity is high because misuse by an AI agent could prematurely kill critical orchestration workers in an enterprise environment, disrupting workflows.
From the tool's definition 'Cancel a running worker' — cancelling an active worker terminates its execution irreversibly, losing in-progress work and state
Attacks that exploit this kind of access
Cancel a running worker Use when native Bash hooks (via Claude Code\. It is categorised as a Destructive tool in the Claude Flow MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the Claude Flow MCP server in PolicyLayer and add a rule for hooks_worker-cancel: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Claude Flow. Nothing to install.
hooks_worker-cancel is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.
Yes. Add a rate_limit block to the hooks_worker-cancel rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for hooks_worker-cancel. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
hooks_worker-cancel is provided by the Claude Flow MCP server (claude-flow). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.