run_command · MCP-Server-Filesystem MCP: Risk & Policy

WHAT IT DOES

What run_command does on MCP-Server-Filesystem

AI agents invoke run_command to trigger actions in MCP-Server-Filesystem. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why run_command needs a policy

Executing shell commands is the highest-impact Execute action because it can invoke any system operation, including file manipulation, network access, privilege escalation, or malicious code execution. The blast radius is maximal—an AI agent with access to this tool can compromise the entire system.

From the tool's definition Tool name 'run_command' and description 'Execute shell commands and return their output' explicitly state the ability to run arbitrary shell commands.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

run_command Rate-limited

run_command stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "run_command": {
      "limits": [
        {
          "counter": "run_command_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-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-Server-Filesystem, so you can run agents against it safely.

FAQ

Questions about run_command

What does the run_command tool do? +

Execute shell commands and return their output. This tool allows running. It is categorised as a Execute tool in the MCP-Server-Filesystem MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on run_command? +

Register the MCP-Server-Filesystem MCP server in PolicyLayer and add a rule for run_command: 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-Server-Filesystem. Nothing to install.

What risk level is run_command? +

run_command is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit run_command? +

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

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

run_command is provided by the MCP-Server-Filesystem MCP server (redf0x1/mcp-server-filesystem). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.