Get a paginated list of subscribers who opened a campaign
AI agents call get_campaign_opens 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 engagement data (open events) without creating, modifying, deleting, or executing any operations. It is a pure read operation that queries campaign analytics. No side effects or state changes occur. The blast radius of misuse is limited to unauthorized visibility into campaign performance metrics.
From the tool's definition Tool name is 'get_campaign_opens' and description states 'Get a paginated list of subscribers who opened a campaign' — uses the verb 'Get' and returns a paginated list with no modification.
Attacks that exploit this kind of access
Get a paginated list of subscribers who opened a campaign. 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_campaign_opens: 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_campaign_opens 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_campaign_opens 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_campaign_opens. 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_campaign_opens 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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