Permanently delete a subscriber from a list
AI agents call delete_subscriber to permanently remove resources in Campaign Monitor MCP — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
This tool irreversibly removes subscriber records from the system with no undo capability. While not a financial transaction, the permanent nature of deletion and potential impact on email lists (loss of contact data, campaign history association) qualifies it as Destructive rather than Write. The high severity reflects that misuse could result in unintended loss of valuable subscriber data that cannot be recovered.
From the tool's definition Tool name is 'delete_subscriber' and description states 'Permanently delete a subscriber from a list'. The use of 'Permanently delete' explicitly indicates irreversible data destruction.
Attacks that exploit this kind of access
Permanently delete a subscriber from a list. It is categorised as a Destructive tool in the Campaign Monitor MCP MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the Campaign Monitor MCP server in PolicyLayer and add a rule for delete_subscriber: 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 Campaign Monitor MCP. Nothing to install.
delete_subscriber 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 delete_subscriber 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 delete_subscriber. 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.
delete_subscriber is provided by the Campaign Monitor MCP server (pauliowest/cmon-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.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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