rename_file · Simple MCP: Risk & Policy

WHAT IT DOES

What rename_file does on Simple MCP

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

WHY IT NEEDS A POLICY

Why rename_file needs a policy

Renaming or moving files modifies filesystem state but is not destructive (can be undone by renaming back) and does not delete data. It falls under Write category. Severity is medium because misuse could reorganize critical files, break application paths, or move files to unexpected locations, causing operational disruption but not permanent data loss. Confidence is high due to clear description of the operation.

From the tool's definition Tool name 'rename_file' and description 'Rename or move a file' indicate modification of file metadata and filesystem structure. This is a reversible write operation.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

rename_file Rate-limited

rename_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": {
    "rename_file": {
      "limits": [
        {
          "counter": "rename_file_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 Simple MCP, so you can run agents against it safely.

FAQ

Questions about rename_file

What does the rename_file tool do? +

Rename or move a file. It is categorised as a Write tool in the Simple MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on rename_file? +

Register the Simple MCP server in PolicyLayer and add a rule for rename_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 Simple MCP. Nothing to install.

What risk level is rename_file? +

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

Can I rate-limit rename_file? +

Yes. Add a rate_limit block to the rename_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 rename_file completely? +

Set action: deny in the PolicyLayer policy for rename_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 rename_file? +

rename_file is provided by the Simple MCP server (karar-hayder/simple-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.