gmail.starMessages · Gmail MCP Server MCP: Risk & Policy

WHAT IT DOES

What gmail.starMessages does on Gmail MCP Server

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

WHY IT NEEDS A POLICY

Why gmail.starMessages needs a policy

Starring messages is a write operation that modifies metadata (adds a star flag) to existing email objects. The change is fully reversible (stars can be removed), has no side effects beyond the message object itself, and the blast radius of misuse is minimal—an AI agent could over-star messages or star sensitive content, but this causes no data loss, financial harm, or system compromise.

From the tool's definition Tool name 'starMessages' and description 'Add star to messages or threads' indicate a reversible modification operation that marks or organizes existing messages without deleting, executing code, or affecting financial/sensitive data.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

gmail.starMessages Rate-limited

gmail.starMessages 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.starMessages": {
      "limits": [
        {
          "counter": "gmail.starmessages_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 MCP Server, so you can run agents against it safely.

FAQ

Questions about gmail.starMessages

What does the gmail.starMessages tool do? +

Add star to messages or threads. Requires gmail.labels scope. It is categorised as a Write tool in the Gmail 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 gmail.starMessages? +

Register the Gmail MCP Server MCP server in PolicyLayer and add a rule for gmail.starMessages: 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 MCP Server. Nothing to install.

What risk level is gmail.starMessages? +

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

Can I rate-limit gmail.starMessages? +

Yes. Add a rate_limit block to the gmail.starMessages 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.starMessages completely? +

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

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