mail_mark_read · Hermes Google MCP: Risk & Policy

WHAT IT DOES

What mail_mark_read does on Hermes Google

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

WHY IT NEEDS A POLICY

Why mail_mark_read needs a policy

This tool modifies message state reversibly by changing a label, which constitutes a Write operation. The impact is minimal (only removes unread status, does not delete or move data), resulting in low severity. The confidence is high because the description clearly indicates a state change operation.

From the tool's definition Tool description states it 'Mark[s] a message as read' by removing the UNREAD label, which is a modification of message metadata/state.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

mail_mark_read Rate-limited

mail_mark_read 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": {
    "mail_mark_read": {
      "limits": [
        {
          "counter": "mail_mark_read_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 Hermes Google, so you can run agents against it safely.

FAQ

Questions about mail_mark_read

What does the mail_mark_read tool do? +

Mark a message as read in Hermes's inbox (removes the UNREAD label). It is categorised as a Write tool in the Hermes 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 mail_mark_read? +

Register the Hermes Google MCP server in PolicyLayer and add a rule for mail_mark_read: 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 Hermes Google. Nothing to install.

What risk level is mail_mark_read? +

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

Can I rate-limit mail_mark_read? +

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

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

mail_mark_read is provided by the Hermes Google MCP server (jimmy-larsson/hermes-google). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.