fs_write · Mcp Ssh Tool MCP: Risk & Policy

WHAT IT DOES

What fs_write does on Mcp Ssh Tool

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

WHY IT NEEDS A POLICY

Why fs_write needs a policy

This tool creates or modifies file contents on a remote system, which is reversible (files can be edited or overwritten again). It does not delete data irreversibly, so it is not Destructive. It does not execute arbitrary code or commands, so it is not Execute.

From the tool's definition Tool name 'fs_write' and description 'Writes data to a file on the remote system' indicate file creation or modification. The tool modifies files on a remote system via SSH without permanently deleting them.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

fs_write Rate-limited

fs_write 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": {
    "fs_write": {
      "limits": [
        {
          "counter": "fs_write_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 Mcp Ssh Tool, so you can run agents against it safely.

FAQ

Questions about fs_write

What does the fs_write tool do? +

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

How do I enforce a policy on fs_write? +

Register the Mcp Ssh Tool MCP server in PolicyLayer and add a rule for fs_write: 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 Mcp Ssh Tool. Nothing to install.

What risk level is fs_write? +

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

Can I rate-limit fs_write? +

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

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

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