flip_horizontal

THE RISK

Medium Risk

Why flip_horizontal needs a policy

This tool modifies existing pixel art data (frames) by applying a geometric transformation. While reversible (flipping twice returns the original state), it constitutes a Write operation because it alters the project's visual content.

From the tool's definition flip_horizontal modifies frame data by transforming pixel positions horizontally. The description states it will 'flip a frame horizontally' and 'supports applying to all frames', indicating direct modification of project state.

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

POLICY

How to control flip_horizontal

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

policy.json

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

flip_horizontal 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 Piskel MCP Server — 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 Piskel MCP Server tools

Destructive delete_project Delete a project Destructive remove_frame Remove a frame from all layers Destructive remove_layer Remove a layer from the project Destructive remove_palette_color Remove a color from a palette Write clear_frame Clear all pixels in a frame Write erase_pixel Erase pixels (set to transparent) Write hue_shift_recolor Recolor sprites by shifting hue. Reads PNGs from an input folder, shifts pixels in a sourc Write add_frame Add a new frame to a layer

All 45 Piskel MCP Server tools →

Write tools on other servers

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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 flip_horizontal

What does the flip_horizontal tool do? +

Flip a frame horizontally (mirror left-right). Supports applying to all frames. It is categorised as a Write tool in the Piskel MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on flip_horizontal? +

Register the Piskel MCP Server MCP server in PolicyLayer and add a rule for flip_horizontal: 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 Piskel MCP Server. Nothing to install.

What risk level is flip_horizontal? +

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

Can I rate-limit flip_horizontal? +

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

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

flip_horizontal is provided by the Piskel MCP Server MCP server (yafeiaa/piskel-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Piskel MCP Server tool call.

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

CHECK YOUR STACK →