send_group_message · iMessage MCP Server MCP: Risk & Policy

WHAT IT DOES

What send_group_message does on iMessage MCP Server

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

WHY IT NEEDS A POLICY

Why send_group_message needs a policy

This tool sends messages to group chats, which creates new data (message records) in the iMessage database. It is reversible (messages can be deleted or edited later) and has no financial impact. While it could be misused to send unwanted messages at scale, the blast radius is limited to messaging operations on a single macOS system.

From the tool's definition Tool name 'send_group_message' and description 'Send a message to a named group chat' indicate this tool creates/modifies data by adding messages to group conversations.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

send_group_message Rate-limited

send_group_message 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": {
    "send_group_message": {
      "limits": [
        {
          "counter": "send_group_message_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 iMessage MCP Server, so you can run agents against it safely.

FAQ

Questions about send_group_message

What does the send_group_message tool do? +

Send a message to a named group chat. It is categorised as a Write tool in the iMessage MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on send_group_message? +

Register the iMessage MCP Server MCP server in PolicyLayer and add a rule for send_group_message: 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 iMessage MCP Server. Nothing to install.

What risk level is send_group_message? +

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

Can I rate-limit send_group_message? +

Yes. Add a rate_limit block to the send_group_message 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 send_group_message completely? +

Set action: deny in the PolicyLayer policy for send_group_message. 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 send_group_message? +

send_group_message is provided by the iMessage MCP Server MCP server (viraatdas/imessage-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.