prepare_send_email · Google MCP: Risk & Policy

WHAT IT DOES

What prepare_send_email does on Google

AI agents use prepare_send_email 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 prepare_send_email needs a policy

The tool creates or modifies email content reversibly before sending, fitting the Write category. Severity is medium rather than high because: (1) the tool requires explicit confirmation before sending, (2) email is generally reversible to some degree (can be unsent in many systems shortly after sending), and (3) the blast radius is limited to communications rather than system-level or financial impacts.

From the tool's definition Tool name is 'prepare_send_email' and description states it 'Prepare email for sending'. This involves composing/creating email content (Write action).

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

prepare_send_email Rate-limited

prepare_send_email 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": {
    "prepare_send_email": {
      "limits": [
        {
          "counter": "prepare_send_email_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 prepare_send_email

What does the prepare_send_email tool do? +

✅ SAFE: Prepare email for sending - shows preview and requires confirmation. 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 prepare_send_email? +

Register the Google MCP server in PolicyLayer and add a rule for prepare_send_email: 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 prepare_send_email? +

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

Can I rate-limit prepare_send_email? +

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

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

prepare_send_email 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.