ftp_patch_file · Ftp MCP: Risk & Policy

WHAT IT DOES

What ftp_patch_file does on Ftp

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

WHY IT NEEDS A POLICY

Why ftp_patch_file needs a policy

This tool modifies remote file content through patch application, which is a Write operation (reversible modification). However, severity is rated high rather than medium because: (1) it operates on production remote systems via FTP/SFTP with no apparent confirmation or rollback mechanisms, (2) patch application can corrupt files if applied to wrong targets or in wrong order, (3) widespread file modifications could…

From the tool's definition Tool description explicitly states it 'Apply[s] a Unified Diff patch to a remote file' and 'updating existing files'. The recommendation to use this 'instead of ftp_put_contents for updating existing files' confirms it modifies remote file content.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

ftp_patch_file Rate-limited

ftp_patch_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": {
    "ftp_patch_file": {
      "limits": [
        {
          "counter": "ftp_patch_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 Ftp, so you can run agents against it safely.

FAQ

Questions about ftp_patch_file

What does the ftp_patch_file tool do? +

Apply a Unified Diff patch to a remote file. RECOMMENDED: Use this instead of ftp_put_contents for updating existing files to minimize bandwidth and ensure atomic-like updates. For new files, use ftp_put_contents. It is categorised as a Write tool in the Ftp MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on ftp_patch_file? +

Register the Ftp MCP server in PolicyLayer and add a rule for ftp_patch_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 Ftp. Nothing to install.

What risk level is ftp_patch_file? +

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

Can I rate-limit ftp_patch_file? +

Yes. Add a rate_limit block to the ftp_patch_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 ftp_patch_file completely? +

Set action: deny in the PolicyLayer policy for ftp_patch_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 ftp_patch_file? +

ftp_patch_file is provided by the Ftp MCP server (kynlos/ftp-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.