move_node · Pen MCP: Risk & Policy

WHAT IT DOES

What move_node does on Pen

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

WHY IT NEEDS A POLICY

Why move_node needs a policy

Moving a node changes the document structure reversibly (a node can be moved back to its original location). This is a modification operation without permanent deletion or irreversible data loss, placing it in the Write category rather than Destructive. The severity is medium because incorrect moves could disrupt document organization or logic flow, but the operation is reversible.

From the tool's definition Tool description states 'Move a node to a new parent (or root level) in an .op file' — this modifies the structure and location of data within a document without deleting or creating new nodes.

Risk signalsAdmin/system-level operation

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

move_node Rate-limited

move_node 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": {
    "move_node": {
      "limits": [
        {
          "counter": "move_node_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 Pen, so you can run agents against it safely.

FAQ

Questions about move_node

What does the move_node tool do? +

Move a node to a new parent (or root level) in an .op file. Optionally specify insertion index. It is categorised as a Write tool in the Pen MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on move_node? +

Register the Pen MCP server in PolicyLayer and add a rule for move_node: 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 Pen. Nothing to install.

What risk level is move_node? +

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

Can I rate-limit move_node? +

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

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

move_node is provided by the Pen MCP server (@zseven-w/pen-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.