merge_visible_layers

THE RISK

Medium Risk

Why merge_visible_layers needs a policy

This tool modifies image data by combining layers, which is a Write operation (creates/modifies data reversibly within the GIMP session). While the merge itself cannot be undone without undo history, the tool does not permanently delete files or commit external state changes.

From the tool's definition merge_visible_layers merges all visible layers into a single layer, which modifies the image structure irreversibly within the GIMP document.

Documented attack patterns abuse exactly the kind of access merge_visible_layers gives an agent:

POLICY

How to control merge_visible_layers

PolicyLayer is an MCP gateway — it sits between your AI agents and Gimp, and nothing reaches the server without passing your rules. This is the rule we recommend for merge_visible_layers:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "merge_visible_layers": {
      "limits": [
        {
          "counter": "merge_visible_layers_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

merge_visible_layers 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.

Create a free account and register Gimp — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Gimp tools

Destructive delete_layer Delete a layer from an image. Parameters: - layer_name: Name of the layer to dele Execute restart_server Drop and re-establish the connection to the GIMP MCP plugin. Use this when: - GIM Execute scale_image scale_image Execute call_api call_api Execute invert_selection Invert the current selection (select what is not selected). Parameters: - image_i Execute open_image Open an image file in GIMP and create a display window. Parameters: - file_path: Execute select_by_color select_by_color Execute select_rectangle select_rectangle

All 79 Gimp tools →

Write tools on other servers

M-Team MCP Server download_torrent YouTube MCP Server generate_video_title Android Forensics ADB MCP Server combine_reports 0xarchive web3_signup

Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about merge_visible_layers

What does the merge_visible_layers tool do? +

Merge all visible layers into a single layer. Parameters: - image_index: Target image index (default 0) Returns: {layer_name, layer_id}. It is categorised as a Write tool in the Gimp MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on merge_visible_layers? +

Register the Gimp MCP server in PolicyLayer and add a rule for merge_visible_layers: 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 Gimp. Nothing to install.

What risk level is merge_visible_layers? +

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

Can I rate-limit merge_visible_layers? +

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

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

merge_visible_layers is provided by the Gimp MCP server (maorcc/gimp-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Gimp tool call.

Start from Gimp, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →