create_reply · Google MCP: Risk & Policy

WHAT IT DOES

What create_reply does on Google

AI agents use create_reply 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 create_reply needs a policy

Creating a reply to an existing comment is a write operation—it adds data to the system but does not execute arbitrary code, delete data, or move money. The severity is low because comment replies have minimal blast radius; they are visible metadata changes with no impact on file content, user permissions, or financial systems.

From the tool's definition The tool description states 'Reply to a comment on a Google Drive file.' This is a write operation that creates new comment reply data. It modifies the comment thread by adding a reply, which is a reversible write action.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

create_reply Rate-limited

create_reply 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": {
    "create_reply": {
      "limits": [
        {
          "counter": "create_reply_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 create_reply

What does the create_reply tool do? +

Reply to a comment on a Google Drive file. 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 create_reply? +

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

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

Can I rate-limit create_reply? +

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

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

create_reply is provided by the Google MCP server (ztgluis/google-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.