merge_stl · Kiln MCP: Risk & Policy

WHAT IT DOES

What merge_stl does on Kiln

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

WHY IT NEEDS A POLICY

Why merge_stl needs a policy

The name implies merging STL (3D model) files, which is a write/modification operation on model data. Without a description, confidence is reduced. Merging files is reversible (original files may still exist), so Write is most appropriate. Not classified as Execute since no code execution or printer command is implied by the name alone.

From the tool's definition Tool name 'merge_stl' suggests combining STL files; description is empty and uninformative.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

merge_stl Rate-limited

merge_stl 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": {
    "merge_stl": {
      "limits": [
        {
          "counter": "merge_stl_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 Kiln, so you can run agents against it safely.

FAQ

Questions about merge_stl

What does the merge_stl tool do? +

merge_stl. It is categorised as a Write tool in the Kiln MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on merge_stl? +

Register the Kiln MCP server in PolicyLayer and add a rule for merge_stl: 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 Kiln. Nothing to install.

What risk level is merge_stl? +

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

Can I rate-limit merge_stl? +

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

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

merge_stl is provided by the Kiln MCP server (codeofaxel/Kiln). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.