update_library · Plex MCP: Risk & Policy

WHAT IT DOES

What update_library does on PlexMCP

AI agents use update_library to create or update resources in PlexMCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your PlexMCP environment.

WHY IT NEEDS A POLICY

Why update_library needs a policy

This tool modifies library configuration settings (Write category), which could affect how media is organized, displayed, or processed. While reversible, misuse could cause disruption to library organization or access. Severity is medium because the changes are constrained to settings (not arbitrary code execution) and are reversible, though the blast radius could affect all users accessing that library.

From the tool's definition Tool name 'update_library' and description 'Update a library's settings' indicate modification of existing configuration data. The term 'update' is explicit that this performs reversible changes to library settings rather than retrieval or deletion.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_library Rate-limited

update_library stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "update_library": {
      "limits": [
        {
          "counter": "update_library_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches PlexMCP, so you can run agents against it safely.

FAQ

Questions about update_library

What does the update_library tool do? +

Update a library's settings. It is categorised as a Write tool in the PlexMCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on update_library? +

Register the Plex MCP server in PolicyLayer and add a rule for update_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 PlexMCP. Nothing to install.

What risk level is update_library? +

update_library is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit update_library? +

Yes. Add a rate_limit block to the update_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 update_library completely? +

Set action: deny in the PolicyLayer policy for update_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 update_library? +

update_library is provided by the Plex MCP server (sandraschi/plexmcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.