gmail_reply_to_message · Google MCP: Risk & Policy

WHAT IT DOES

What gmail_reply_to_message does on Google

AI agents use gmail_reply_to_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_reply_to_message needs a policy

This tool writes/creates new data (email reply) reversibly. While email can technically be deleted later, the primary action is composing and sending a message, which is a write operation.

From the tool's definition Tool name 'gmail_reply_to_message' and description 'Reply to a Gmail message' indicate the tool creates a new email message in response to an existing one, modifying the email thread.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

gmail_reply_to_message Rate-limited

gmail_reply_to_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_reply_to_message": {
      "limits": [
        {
          "counter": "gmail_reply_to_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_reply_to_message

What does the gmail_reply_to_message tool do? +

Reply to 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_reply_to_message? +

Register the Google MCP server in PolicyLayer and add a rule for gmail_reply_to_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_reply_to_message? +

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

Can I rate-limit gmail_reply_to_message? +

Yes. Add a rate_limit block to the gmail_reply_to_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_reply_to_message completely? +

Set action: deny in the PolicyLayer policy for gmail_reply_to_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_reply_to_message? +

gmail_reply_to_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.