crow_calibre_list_categories

THE RISK

Low Risk

Why crow_calibre_list_categories needs a policy

This tool performs a read-only query of library metadata structure. It retrieves informational data about available categories without creating, modifying, deleting, or executing any operations. The blast radius of misuse is minimal - an AI agent could only discover what categories exist in the library, posing no security or operational risk.

From the tool's definition Tool description states 'List available categories in the Calibre library' - this is a retrieval operation that queries metadata (authors, tags, series, publishers, languages, ratings) with no modification or side effects.

Documented attack patterns abuse exactly the kind of access crow_calibre_list_categories gives an agent:

POLICY

How to control crow_calibre_list_categories

PolicyLayer is an MCP gateway — it sits between your AI agents and Crow, and nothing reaches the server without passing your rules. This is the rule we recommend for crow_calibre_list_categories:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "crow_calibre_list_categories": {}
  }
}

crow_calibre_list_categories is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register Crow — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

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EXPLORE

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FAQ

Questions about crow_calibre_list_categories

What does the crow_calibre_list_categories tool do? +

List available categories in the Calibre library (authors, tags, series, publishers, languages, ratings). It is categorised as a Read tool in the Crow MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on crow_calibre_list_categories? +

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

What risk level is crow_calibre_list_categories? +

crow_calibre_list_categories is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit crow_calibre_list_categories? +

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

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

crow_calibre_list_categories is provided by the Crow MCP server (kh0pper/crow). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Crow tool call.

Start from Crow, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

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