Get the campaign history for a subscriber in a list
AI agents call get_subscriber_history to retrieve information from Campaign Monitor MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves historical campaign data for a subscriber. The verb 'Get' and the absence of any language suggesting modification, deletion, or execution (create, update, delete, execute) clearly place this in the Read category. The data retrieved is historical campaign information, which poses minimal risk if accessed by an AI agent, as it cannot alter state or trigger external operations.
From the tool's definition Tool name is 'get_subscriber_history' and description states 'Get the campaign history for a subscriber in a list' — both indicate a retrieval operation with no modification of data.
Attacks that exploit this kind of access
Get the campaign history for a subscriber in a list. It is categorised as a Read tool in the Campaign Monitor MCP MCP Server, which means it retrieves data without modifying state.
Register the Campaign Monitor MCP server in PolicyLayer and add a rule for get_subscriber_history: 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.
get_subscriber_history is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the get_subscriber_history 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 get_subscriber_history. 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.
get_subscriber_history 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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