export_png · AI-Canvas MCP Server MCP: Risk & Policy

WHAT IT DOES

What export_png does on AI-Canvas MCP Server

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

WHY IT NEEDS A POLICY

Why export_png needs a policy

This tool creates (writes) new PNG image files as exports from design nodes. While it does not modify the original design document itself, it generates new binary artifacts that are stored, making it a Write operation. Severity is medium because exporting designs could expose proprietary design data, but the operation is reversible (exported files can be deleted) and has no destructive or financial impact.

From the tool's definition Tool name 'export_png' and description 'Export design nodes to PNG images' indicate creation of new image files from design data.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

export_png Rate-limited

export_png 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": {
    "export_png": {
      "limits": [
        {
          "counter": "export_png_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 AI-Canvas MCP Server, so you can run agents against it safely.

FAQ

Questions about export_png

What does the export_png tool do? +

Export design nodes to PNG images. It is categorised as a Write tool in the AI-Canvas 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 export_png? +

Register the AI-Canvas MCP Server MCP server in PolicyLayer and add a rule for export_png: 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 AI-Canvas MCP Server. Nothing to install.

What risk level is export_png? +

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

Can I rate-limit export_png? +

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

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

export_png is provided by the AI-Canvas MCP Server MCP server (laoluojuhai/ai-canvas). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.