rhino_arc

Add an arc by centre, radius, and sweep angle (in degrees).

SERVERRhino SOURCEeasehee/rhino-mcp

Medium RISK CLASS

Category Write

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/easehee-rhino-mcp/rhino-arc.md

WHAT IT DOES

What rhino_arc does on Rhino

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

RISK

Why rhino_arc is rated Medium

The tool creates new geometry (an arc) in Rhino's model space, which is a data creation action. This falls under Write rather than Execute because it performs a specific, well-defined geometric operation rather than arbitrary code execution. It is reversible (undo is available in Rhino), so it does not qualify as Destructive.

From the tool's definition Tool description states 'Add an arc' - the verb 'add' indicates creation of new geometry data in Rhino. This is a reversible operation that modifies the model state by inserting a new geometric object.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs rhino_arc safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Rhino, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For rhino_arc, this is the rule to start with:

rhino_arc Rate-limited

rhino_arc 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": {
    "rhino_arc": {
      "limits": [
        {
          "counter": "rhino_arc_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Rhino, apply this rule, and every rhino_arc call is checked against it from then on.

FAQ

Questions about rhino_arc

What does the rhino_arc tool do? +

Add an arc by centre, radius, and sweep angle (in degrees). It is categorised as a Write tool in the Rhino MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on rhino_arc? +

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

What risk level is rhino_arc? +

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

Can I rate-limit rhino_arc? +

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

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

rhino_arc is provided by the Rhino MCP server (easehee/rhino-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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