draw_polygon · Open Brush MCP Server MCP: Risk & Policy

WHAT IT DOES

What draw_polygon does on Open Brush MCP Server

AI agents invoke draw_polygon to trigger actions in Open Brush MCP Server. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why draw_polygon needs a policy

This tool executes an external operation in the Open Brush 3D painting software, causing it to render/draw a polygon. It's not a simple data write to a database but rather triggers a real-time graphical action in an external application. Misuse could result in unwanted content being drawn in an active scene, but the effect is reversible (can be undone), keeping severity at medium.

From the tool's definition 'Draws a polygon at the current brush position' — triggers an external drawing operation in Open Brush via HTTP API

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

draw_polygon Rate-limited

draw_polygon stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "draw_polygon": {
      "limits": [
        {
          "counter": "draw_polygon_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Open Brush MCP Server, so you can run agents against it safely.

FAQ

Questions about draw_polygon

What does the draw_polygon tool do? +

Draws a polygon at the current brush position. It is categorised as a Execute tool in the Open Brush MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on draw_polygon? +

Register the Open Brush MCP Server MCP server in PolicyLayer and add a rule for draw_polygon: 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 Open Brush MCP Server. Nothing to install.

What risk level is draw_polygon? +

draw_polygon is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit draw_polygon? +

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

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

draw_polygon is provided by the Open Brush MCP Server MCP server (moz411/openbrush-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.