prepare_share_file · Google MCP: Risk & Policy

WHAT IT DOES

What prepare_share_file does on Google

AI agents use prepare_share_file 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 prepare_share_file needs a policy

The tool prepares to share a file, which modifies access permissions or sharing state of a file (a reversible write operation). The description notes it shows a preview and requires confirmation, suggesting it doesn't immediately execute but sets up a sharing action. Since sharing a file changes its visibility/access settings, this is a Write-category action.

From the tool's definition 'Prepare file sharing - shows preview and requires confirmation'

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

prepare_share_file Rate-limited

prepare_share_file 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": {
    "prepare_share_file": {
      "limits": [
        {
          "counter": "prepare_share_file_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 Google, so you can run agents against it safely.

FAQ

Questions about prepare_share_file

What does the prepare_share_file tool do? +

✅ SAFE: Prepare file sharing - shows preview and requires confirmation. 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 prepare_share_file? +

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

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

Can I rate-limit prepare_share_file? +

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

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

prepare_share_file 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.

// THE FULL RECORD

prepare_share_file is one line of Google's registry record.

The record carries the whole server: verified identity, auth posture, risk grade, every tool classified, recommended policy — re-checked continuously.

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