modify_email · Gmail MCP: Risk & Policy

WHAT IT DOES

What modify_email does on Gmail

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

WHY IT NEEDS A POLICY

Why modify_email needs a policy

Modifying labels is a write operation that reorganizes data. It is reversible (labels can be changed back), so it does not meet the Destructive threshold. It does not execute code, move money, or trigger external operations beyond Gmail's label system.

From the tool's definition Tool description states it 'Modifies email labels (move to different folders)' — this is a reversible modification operation that changes email metadata/organization without deleting or executing arbitrary code.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

modify_email Rate-limited

modify_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": {
    "modify_email": {
      "limits": [
        {
          "counter": "modify_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 Gmail, so you can run agents against it safely.

FAQ

Questions about modify_email

What does the modify_email tool do? +

Modifies email labels (move to different folders). It is categorised as a Write tool in the Gmail MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on modify_email? +

Register the Gmail MCP server in PolicyLayer and add a rule for modify_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 Gmail. Nothing to install.

What risk level is modify_email? +

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

Can I rate-limit modify_email? +

Yes. Add a rate_limit block to the modify_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 modify_email completely? +

Set action: deny in the PolicyLayer policy for modify_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 modify_email? +

modify_email is provided by the Gmail MCP server (pouyanafisi/gmail-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.