Cancels an active Jules session.
AI agents call jules_cancel_session to permanently remove resources in Jules MCP Server — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
Cancelling an active session is a destructive action because it irreversibly terminates the session. Any in-progress AI-generated work or state within that session would be lost. While it does not delete files or data directly, the action cannot be undone (the session cannot be 'uncancelled'), placing it in the Destructive category over mere Write.
From the tool's definition 'Cancels an active Jules session' — cancellation of a session is irreversible; the active session and any associated in-progress work would be terminated and cannot be resumed.
Attacks that exploit this kind of access
Cancels an active Jules session. It is categorised as a Destructive tool in the Jules MCP Server MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the Jules MCP Server MCP server in PolicyLayer and add a rule for jules_cancel_session: 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 Jules MCP Server. Nothing to install.
jules_cancel_session 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 jules_cancel_session 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 jules_cancel_session. 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.
jules_cancel_session is provided by the Jules MCP Server MCP server (streetquant/jules-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
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