add_nodes · Draw Io MCP Server MCP: Risk & Policy

WHAT IT DOES

What add_nodes does on Draw Io MCP Server

AI agents use add_nodes 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 add_nodes needs a policy

The tool creates or modifies diagram content reversibly by adding nodes to an existing diagram file. This is a Write operation (create/modify data without deletion). Severity is low because the worst-case misuse would be adding unwanted diagram elements, which can be easily undone by removing nodes or reverting the file. There is no code execution, data destruction, or financial impact.

From the tool's definition Tool description states it 'Add[s] one or more nodes to a diagram file', which is a create/modify operation on diagram data. The server description confirms these are 'stateless operations that generate VSCode-compatible .drawio.svg files'.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

add_nodes Rate-limited

add_nodes 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": {
    "add_nodes": {
      "limits": [
        {
          "counter": "add_nodes_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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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 add_nodes

What does the add_nodes tool do? +

Add one or more nodes to a diagram file. Optionally run an automatic layout after insertion. 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 add_nodes? +

Register the Draw Io MCP Server MCP server in PolicyLayer and add a rule for add_nodes: 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 add_nodes? +

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

Can I rate-limit add_nodes? +

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

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

add_nodes 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.