container_check_updates · Homelab MCP: Risk & Policy

WHAT IT DOES

What container_check_updates does on Homelab

AI agents invoke container_check_updates to trigger actions in Homelab. 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 container_check_updates needs a policy

Pulling images is not a passive read; it executes an outbound network operation that downloads and stores new image layers on the host. While it doesn't replace running containers, it modifies local Docker image storage and triggers external operations, placing it in Execute.

From the tool's definition 'Pull latest images for all running containers on the devbox' — actively pulls Docker images from remote registries, triggering external network operations

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

container_check_updates Rate-limited

container_check_updates 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": {
    "container_check_updates": {
      "limits": [
        {
          "counter": "container_check_updates_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 Homelab, so you can run agents against it safely.

FAQ

Questions about container_check_updates

What does the container_check_updates tool do? +

Pull latest images for all running containers on the devbox and report which have updates available. It is categorised as a Execute tool in the Homelab MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on container_check_updates? +

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

What risk level is container_check_updates? +

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

Can I rate-limit container_check_updates? +

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

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

container_check_updates is provided by the Homelab MCP server (nainounen/homelab-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.