write-file · Ssh MCP: Risk & Policy

WHAT IT DOES

What write-file does on Ssh

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

WHY IT NEEDS A POLICY

Why write-file needs a policy

This tool creates or modifies files on remote servers, which is a reversible write operation. Severity is high because unauthorized file writes on remote systems could modify critical application configuration, inject malicious code into source files, or corrupt data, though the operation is technically reversible (files can be deleted or overwritten).

From the tool's definition Tool name is 'write-file' and description states 'Write content to a file on the remote server' - explicitly creates or modifies data on a remote system.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

write-file Rate-limited

write-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": {
    "write-file": {
      "limits": [
        {
          "counter": "write-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 Ssh, so you can run agents against it safely.

FAQ

Questions about write-file

What does the write-file tool do? +

Write content to a file on the remote server. It is categorised as a Write tool in the Ssh MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on write-file? +

Register the Ssh MCP server in PolicyLayer and add a rule for write-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 Ssh. Nothing to install.

What risk level is write-file? +

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

Can I rate-limit write-file? +

Yes. Add a rate_limit block to the write-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 write-file completely? +

Set action: deny in the PolicyLayer policy for write-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 write-file? +

write-file is provided by the Ssh MCP server (zachflint/ssh-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.