move_file · Nexus Core MCP: Risk & Policy

WHAT IT DOES

What move_file does on Nexus Core

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

WHY IT NEEDS A POLICY

Why move_file needs a policy

Moving or renaming a file modifies filesystem state but is reversible—the original data persists at a new location and can be moved back. This is a Write operation, not Destructive, because: (1) data is not deleted or lost, (2) the operation can be undone by moving the file back, and (3) the tool explicitly refuses overwrite, preventing data loss.

From the tool's definition Tool description explicitly states "MOVE/RENAME a file" with validation and overwrite protection. These are reversible file operations.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

move_file Rate-limited

move_file 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_file": {
      "limits": [
        {
          "counter": "move_file_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 Nexus Core, so you can run agents against it safely.

FAQ

Questions about move_file

What does the move_file tool do? +

MOVE/RENAME a file. Both paths must validate. Refuses to overwrite an existing file at destination. It is categorised as a Write tool in the Nexus Core 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_file? +

Register the Nexus Core MCP server in PolicyLayer and add a rule for move_file: 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 Nexus Core. Nothing to install.

What risk level is move_file? +

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

Can I rate-limit move_file? +

Yes. Add a rate_limit block to the move_file 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_file completely? +

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

move_file is provided by the Nexus Core MCP server (noumenon-ai/nexus-core). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.