draw_stroke · Open Brush MCP Server MCP: Risk & Policy

WHAT IT DOES

What draw_stroke does on Open Brush MCP Server

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

WHY IT NEEDS A POLICY

Why draw_stroke needs a policy

This tool creates a new stroke in the 3D painting application. It writes/creates new content (a stroke) in the canvas. While it modifies the painting state, strokes can typically be undone in creative applications, making this Write rather than Destructive. The blast radius is medium as misuse could undesirably alter an artwork in progress.

From the tool's definition Draws an exact stroke with orientation and pressure

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

draw_stroke Rate-limited

draw_stroke 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_stroke": {
      "limits": [
        {
          "counter": "draw_stroke_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 Open Brush MCP Server, so you can run agents against it safely.

FAQ

Questions about draw_stroke

What does the draw_stroke tool do? +

Draws an exact stroke with orientation and pressure. It is categorised as a Write tool in the Open Brush MCP Server 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_stroke? +

Register the Open Brush MCP Server MCP server in PolicyLayer and add a rule for draw_stroke: 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 Open Brush MCP Server. Nothing to install.

What risk level is draw_stroke? +

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

Can I rate-limit draw_stroke? +

Yes. Add a rate_limit block to the draw_stroke 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_stroke completely? +

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

draw_stroke is provided by the Open Brush MCP Server MCP server (moz411/openbrush-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.