faber_service_restart · Faber MCP Server MCP: Risk & Policy

WHAT IT DOES

What faber_service_restart does on Faber MCP Server

AI agents invoke faber_service_restart to trigger actions in Faber MCP Server. 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 faber_service_restart needs a policy

This tool executes a restart command on production infrastructure services. While not permanently destructive or financially harmful, it can cause service downtime, dropped connections, and interrupted operations depending on how the restart is performed. The blast radius is significant—restarting mysql or nginx in a production environment can impact all dependent applications.

From the tool's definition The tool name 'faber_service_restart' and description 'Restart a system service (nginx, php, mysql, supervisor, redis)' indicate it triggers external operations with side effects.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

faber_service_restart Rate-limited

faber_service_restart 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": {
    "faber_service_restart": {
      "limits": [
        {
          "counter": "faber_service_restart_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 Faber MCP Server, so you can run agents against it safely.

FAQ

Questions about faber_service_restart

What does the faber_service_restart tool do? +

Restart a system service (nginx, php, mysql, supervisor, redis). It is categorised as a Execute tool in the Faber MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on faber_service_restart? +

Register the Faber MCP Server MCP server in PolicyLayer and add a rule for faber_service_restart: 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 Faber MCP Server. Nothing to install.

What risk level is faber_service_restart? +

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

Can I rate-limit faber_service_restart? +

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

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

faber_service_restart is provided by the Faber MCP Server MCP server (joshtrebilco/faber-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.