replace_image · Google MCP: Risk & Policy

WHAT IT DOES

What replace_image does on Google

AI agents use replace_image 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 replace_image needs a policy

This tool modifies document content by replacing an image, which is a reversible write operation. It does not delete the document or image permanently (would be Destructive), nor does it execute arbitrary code (would be Execute).

From the tool's definition Tool name is 'replace_image' and description states it will 'Replace an existing image in a Google Doc.' The verb 'replace' indicates modification of existing content rather than creation or deletion.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

replace_image Rate-limited

replace_image 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": {
    "replace_image": {
      "limits": [
        {
          "counter": "replace_image_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 replace_image

What does the replace_image tool do? +

Replace an existing image in a Google Doc. 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 replace_image? +

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

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

Can I rate-limit replace_image? +

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

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

replace_image 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.