add_segment_rule_group · Campaign Monitor MCP: Risk & Policy

WHAT IT DOES

What add_segment_rule_group does on Campaign Monitor MCP

AI agents use add_segment_rule_group to create or update resources in Campaign Monitor MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Campaign Monitor MCP environment.

WHY IT NEEDS A POLICY

Why add_segment_rule_group needs a policy

This tool creates or modifies segment rules, which are data structures that define audience targeting criteria. While the operation is reversible (rules can be removed or modified), it affects email campaign targeting logic and could impact which subscribers receive communications.

From the tool's definition 'Add a rule group to an existing segment' modifies an existing segment by adding rules, which is a reversible create/update operation on segment configuration.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

add_segment_rule_group Rate-limited

add_segment_rule_group stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "add_segment_rule_group": {
      "limits": [
        {
          "counter": "add_segment_rule_group_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Campaign Monitor MCP, so you can run agents against it safely.

FAQ

Questions about add_segment_rule_group

What does the add_segment_rule_group tool do? +

Add a rule group to an existing segment. It is categorised as a Write tool in the Campaign Monitor MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on add_segment_rule_group? +

Register the Campaign Monitor MCP server in PolicyLayer and add a rule for add_segment_rule_group: 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.

What risk level is add_segment_rule_group? +

add_segment_rule_group is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit add_segment_rule_group? +

Yes. Add a rate_limit block to the add_segment_rule_group 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.

How do I block add_segment_rule_group completely? +

Set action: deny in the PolicyLayer policy for add_segment_rule_group. 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.

What MCP server provides add_segment_rule_group? +

add_segment_rule_group 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.