convert_image · Nanobanana Pro MCP: Risk & Policy

WHAT IT DOES

What convert_image does on Nanobanana Pro

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

WHY IT NEEDS A POLICY

Why convert_image needs a policy

convert_image performs data transformation that creates new files or overwrites existing ones through format conversion and icon generation. This is reversible (files can be reconverted or deleted), making it Write rather than Destructive. It does not execute arbitrary code, access sensitive data, or trigger financial transactions.

From the tool's definition Tool description states 'Convert an image file to a different format' and 'automatically generates all required size variants.' This modifies or creates new image assets through format conversion and resizing operations.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

convert_image Rate-limited

convert_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": {
    "convert_image": {
      "limits": [
        {
          "counter": "convert_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 Nanobanana Pro, so you can run agents against it safely.

FAQ

Questions about convert_image

What does the convert_image tool do? +

Convert an image file to a different format. Supports: png, jpg, webp, ico (Windows icon with multiple sizes), icns (macOS icon). For ico/icns, automatically generates all required size variants. It is categorised as a Write tool in the Nanobanana Pro MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on convert_image? +

Register the Nanobanana Pro MCP server in PolicyLayer and add a rule for convert_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 Nanobanana Pro. Nothing to install.

What risk level is convert_image? +

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

Can I rate-limit convert_image? +

Yes. Add a rate_limit block to the convert_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 convert_image completely? +

Set action: deny in the PolicyLayer policy for convert_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 convert_image? +

convert_image is provided by the Nanobanana Pro MCP server (rzgrozt/nanobanana-pro-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.