drive_update · Hermes Google MCP: Risk & Policy

WHAT IT DOES

What drive_update does on Hermes Google

AI agents use drive_update 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 drive_update needs a policy

This tool modifies file contents in Google Drive. While the operation overwrites existing data, it remains Write rather than Destructive because the original file object persists (only contents change), and the action is theoretically reversible through version history or backups.

From the tool's definition Tool description states 'Replace a Drive file's contents with a local file', which is a reversible modification operation. The phrase 'Replace...contents' indicates file overwriting rather than deletion.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

drive_update Rate-limited

drive_update 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": {
    "drive_update": {
      "limits": [
        {
          "counter": "drive_update_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 drive_update

What does the drive_update tool do? +

Replace a Drive file's contents with a local file. Requires user confirmation before calling. 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 drive_update? +

Register the Hermes Google MCP server in PolicyLayer and add a rule for drive_update: 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 drive_update? +

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

Can I rate-limit drive_update? +

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

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

drive_update 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.