hollow_model · Formlabs Local MCP: Risk & Policy

WHAT IT DOES

What hollow_model does on Formlabs Local

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

WHY IT NEEDS A POLICY

Why hollow_model needs a policy

This tool modifies existing model data (hollowing geometry) which is a reversible write operation on the model within the scene. It does not delete or destroy the model entirely, but it does alter its structure. Since the change could potentially be undone by re-importing the original model, it falls under Write rather than Destructive. Misuse could corrupt a model intended for printing, giving it medium severity.

From the tool's definition 'Hollow the specified models to reduce material usage' — modifies the geometry of a 3D model by hollowing it out

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

hollow_model Rate-limited

hollow_model 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": {
    "hollow_model": {
      "limits": [
        {
          "counter": "hollow_model_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 Formlabs Local, so you can run agents against it safely.

FAQ

Questions about hollow_model

What does the hollow_model tool do? +

Hollow the specified models to reduce material usage. It is categorised as a Write tool in the Formlabs Local MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on hollow_model? +

Register the Formlabs Local MCP server in PolicyLayer and add a rule for hollow_model: 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 Formlabs Local. Nothing to install.

What risk level is hollow_model? +

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

Can I rate-limit hollow_model? +

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

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

hollow_model is provided by the Formlabs Local MCP server (mkebiclioglu/formlabs-local-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.