draw_arc · CAD- MCP: Risk & Policy

WHAT IT DOES

What draw_arc does on CAD-MCP

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

WHY IT NEEDS A POLICY

Why draw_arc needs a policy

This tool creates new arc geometry in AutoCAD/GstarCAD/ZWCAD designs. It is a Write operation because it modifies the drawing by adding a new graphical element, but the changes are reversible (users can undo or delete the arc). It is not Destructive because it does not permanently erase data.

From the tool's definition Tool name 'draw_arc' and description '绘制圆弧' (draw arc) with parameters for center, radius, start_angle, end_angle, and optional layer, color, lineweight. Creates new geometry in a CAD design.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

draw_arc Rate-limited

draw_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": {
    "draw_arc": {
      "limits": [
        {
          "counter": "draw_arc_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 CAD-MCP, so you can run agents against it safely.

FAQ

Questions about draw_arc

What does the draw_arc tool do? +

绘制圆弧。参数: center, radius, start_angle, end_angle, layer?, color?, lineweight?. It is categorised as a Write tool in the CAD-MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on draw_arc? +

Register the CAD- MCP server in PolicyLayer and add a rule for draw_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 CAD-MCP. Nothing to install.

What risk level is draw_arc? +

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

Can I rate-limit draw_arc? +

Yes. Add a rate_limit block to the draw_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 draw_arc completely? +

Set action: deny in the PolicyLayer policy for draw_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 draw_arc? +

draw_arc is provided by the CAD- MCP server (piexl/cad-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.