gmail_add_label · Google MCP: Risk & Policy

WHAT IT DOES

What gmail_add_label does on Google

AI agents use gmail_add_label 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_add_label needs a policy

The tool adds labels to Gmail messages, which is a data modification operation. Labels in Gmail are metadata tags that can be added or removed without permanently deleting data, making this a Write operation rather than Destructive.

From the tool's definition 'Add labels to a Gmail message' - this modifies Gmail message metadata by applying labels, which is a reversible write operation on existing data.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

gmail_add_label Rate-limited

gmail_add_label 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_add_label": {
      "limits": [
        {
          "counter": "gmail_add_label_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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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_add_label

What does the gmail_add_label tool do? +

Add labels to a Gmail message (comma-separated label IDs). 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_add_label? +

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

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

Can I rate-limit gmail_add_label? +

Yes. Add a rate_limit block to the gmail_add_label 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_add_label completely? +

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

gmail_add_label 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.