new_diagram · Draw Io MCP Server MCP: Risk & Policy

WHAT IT DOES

What new_diagram does on Draw Io MCP Server

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

WHY IT NEEDS A POLICY

Why new_diagram needs a policy

This tool creates a new file on the filesystem. It is a reversible write operation (the file can be deleted afterward). No existing data is modified or destroyed, no code is executed, and no financial transactions occur. Blast radius is low since it only creates an empty diagram file.

From the tool's definition Create a new empty diagram file

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

new_diagram Rate-limited

new_diagram 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": {
    "new_diagram": {
      "limits": [
        {
          "counter": "new_diagram_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 Draw Io MCP Server, so you can run agents against it safely.

FAQ

Questions about new_diagram

What does the new_diagram tool do? +

Create a new empty diagram file. It is categorised as a Write tool in the Draw Io 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 new_diagram? +

Register the Draw Io MCP Server MCP server in PolicyLayer and add a rule for new_diagram: 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 Draw Io MCP Server. Nothing to install.

What risk level is new_diagram? +

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

Can I rate-limit new_diagram? +

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

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

new_diagram is provided by the Draw Io MCP Server MCP server (noacodenoobe/drawiomcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.