jellyfin.scan_library · Arr Stack MCP: Risk & Policy

WHAT IT DOES

What jellyfin.scan_library does on Arr Stack

AI agents invoke jellyfin.scan_library to trigger actions in Arr Stack. 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 jellyfin.scan_library needs a policy

A 'scan_library' operation typically triggers Jellyfin to scan/index media files, which is an external operation with side effects (re-indexing, updating database). This falls under Execute as it triggers an external operation. However, the empty description significantly reduces confidence. Severity is medium as misuse could cause performance impact or unintended library changes, but is generally reversible.

From the tool's definition Tool name 'scan_library' suggests triggering a library scan operation in Jellyfin; description is empty and uninformative.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

jellyfin.scan_library Rate-limited

jellyfin.scan_library 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": {
    "jellyfin.scan_library": {
      "limits": [
        {
          "counter": "jellyfin.scan_library_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 Arr Stack, so you can run agents against it safely.

FAQ

Questions about jellyfin.scan_library

What does the jellyfin.scan_library tool do? +

jellyfin.scan_library. It is categorised as a Execute tool in the Arr Stack MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on jellyfin.scan_library? +

Register the Arr Stack MCP server in PolicyLayer and add a rule for jellyfin.scan_library: 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 Arr Stack. Nothing to install.

What risk level is jellyfin.scan_library? +

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

Can I rate-limit jellyfin.scan_library? +

Yes. Add a rate_limit block to the jellyfin.scan_library 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 jellyfin.scan_library completely? +

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

jellyfin.scan_library is provided by the Arr Stack MCP server (new-usemame/arr-stack-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.