modifyGmailMessageLabels

THE RISK

Medium Risk

Why modifyGmailMessageLabels needs a policy

This tool modifies Gmail message labels, which is a reversible write operation. While it changes email organization/categorization, it does not execute code, delete messages, move money, or cause destructive changes. The action is easily undoable (labels can be re-added or removed).

From the tool's definition Tool description states "Add or remove labels from a Gmail message" - these are reversible modifications to message metadata. Labels can be added and removed without destroying data or executing code.

Documented attack patterns abuse exactly the kind of access modifyGmailMessageLabels gives an agent:

POLICY

How to control modifyGmailMessageLabels

PolicyLayer is an MCP gateway — it sits between your AI agents and Google Workspace MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for modifyGmailMessageLabels:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "modifyGmailMessageLabels": {
      "limits": [
        {
          "counter": "modifygmailmessagelabels_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

modifyGmailMessageLabels 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.

Create a free account and register Google Workspace MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about modifyGmailMessageLabels

What does the modifyGmailMessageLabels tool do? +

Add or remove labels from a Gmail message. It is categorised as a Write tool in the Google Workspace 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 modifyGmailMessageLabels? +

Register the Google Workspace MCP Server MCP server in PolicyLayer and add a rule for modifyGmailMessageLabels: 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 Workspace MCP Server. Nothing to install.

What risk level is modifyGmailMessageLabels? +

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

Can I rate-limit modifyGmailMessageLabels? +

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

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

modifyGmailMessageLabels is provided by the Google Workspace MCP Server MCP server (sputnicyoji/google-workspace-mcp-with-script). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Google Workspace MCP Server tool call.

Start from Google Workspace MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →