gmail_forward_message · Google MCP: Risk & Policy

WHAT IT DOES

What gmail_forward_message does on Google

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

WHY IT NEEDS A POLICY

Why gmail_forward_message needs a policy

Forwarding a Gmail message is a reversible write operation that creates new data (a forwarded message) but does not delete or modify the original message. The severity is medium because forwarding could expose sensitive information in the forwarded message to unintended recipients if an agent misuses the recipient parameter, but the impact is limited to information disclosure rather than deletion or financial harm.

From the tool's definition The tool name is 'gmail_forward_message' and description states it will 'Forward a Gmail message'. Forwarding creates a new message (Write operation) by copying and relaying an existing message to new recipients.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

gmail_forward_message Rate-limited

gmail_forward_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": {
    "gmail_forward_message": {
      "limits": [
        {
          "counter": "gmail_forward_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 Google, so you can run agents against it safely.

FAQ

Questions about gmail_forward_message

What does the gmail_forward_message tool do? +

Forward a Gmail message. It is categorised as a Write tool in the Google MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on gmail_forward_message? +

Register the Google MCP server in PolicyLayer and add a rule for gmail_forward_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 Google. Nothing to install.

What risk level is gmail_forward_message? +

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

Can I rate-limit gmail_forward_message? +

Yes. Add a rate_limit block to the gmail_forward_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 gmail_forward_message completely? +

Set action: deny in the PolicyLayer policy for gmail_forward_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 gmail_forward_message? +

gmail_forward_message is provided by the Google MCP server (robcerda/google-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.