system_update · Cachyos MCP: Risk & Policy

WHAT IT DOES

What system_update does on Cachyos

AI agents invoke system_update to trigger actions in Cachyos. 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 system_update needs a policy

Running a full system upgrade modifies potentially hundreds of packages system-wide. While technically a Write/Execute operation, it carries critical blast radius: a bad upgrade can break system boot, destabilize running services, introduce incompatible dependencies, or render the system unbootable. It executes privileged package manager commands with broad, hard-to-reverse system-wide effects.

From the tool's definition 'Upgrade the system (pacman -Syu, or paru -Syu with AUR)' — triggers a full system upgrade across all packages

Risk signalsAdmin/system-level operation

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

system_update Rate-limited

system_update 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": {
    "system_update": {
      "limits": [
        {
          "counter": "system_update_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 Cachyos, so you can run agents against it safely.

FAQ

Questions about system_update

What does the system_update tool do? +

[ACTION] Upgrade the system (pacman -Syu, or paru -Syu with AUR). It is categorised as a Execute tool in the Cachyos MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on system_update? +

Register the Cachyos MCP server in PolicyLayer and add a rule for system_update: 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 Cachyos. Nothing to install.

What risk level is system_update? +

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

Can I rate-limit system_update? +

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

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

system_update is provided by the Cachyos MCP server (raindancer118/cachyos-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.