select_ngons · Blender MCP: Risk & Policy

WHAT IT DOES

What select_ngons does on BlenderMCP

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

WHY IT NEEDS A POLICY

Why select_ngons needs a policy

An AI agent can call select_ngons faster than any human can review — one bad instruction and it creates or modifies resources in BlenderMCP by the hundred, each call as confident as the last.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

select_ngons Rate-limited

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

FAQ

Questions about select_ngons

What does the select_ngons tool do? +

Select all n-gon faces (5+ vertices) in the mesh. It is categorised as a Write tool in the BlenderMCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on select_ngons? +

Register the Blender MCP server in PolicyLayer and add a rule for select_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 select_ngons? +

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

Can I rate-limit select_ngons? +

Yes. Add a rate_limit block to the select_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 select_ngons completely? +

Set action: deny in the PolicyLayer policy for select_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 select_ngons? +

select_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.