fix_ngons · Blender MCP: Risk & Policy

WHAT IT DOES

What fix_ngons does on BlenderMCP

AI agents invoke fix_ngons to trigger actions in BlenderMCP. 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 fix_ngons needs a policy

The tool name 'fix_ngons' suggests it performs mesh cleanup operations in Blender (fixing n-gons, which are polygons with more than 4 sides, by converting them to quads or triangles). This modifies 3D mesh data within Blender, which is a Write/Execute operation. Given the server description explicitly mentions executing Python scripts within Blender, this likely runs a script to modify geometry.

From the tool's definition Tool name 'fix_ngons' and server description mentions executing Python scripts directly within Blender environment

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

fix_ngons Rate-limited

fix_ngons 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": {
    "fix_ngons": {
      "limits": [
        {
          "counter": "fix_ngons_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 BlenderMCP, so you can run agents against it safely.

FAQ

Questions about fix_ngons

What does the fix_ngons tool do? +

fix_ngons. It is categorised as a Execute tool in the BlenderMCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on fix_ngons? +

Register the Blender MCP server in PolicyLayer and add a rule for fix_ngons: 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 BlenderMCP. Nothing to install.

What risk level is fix_ngons? +

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

Can I rate-limit fix_ngons? +

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

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

fix_ngons is provided by the Blender MCP server (shirshovdim/retopoflow_blender_mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.