crow_calibreweb_shelves

THE RISK

Low Risk

Why crow_calibreweb_shelves needs a policy

This tool performs a read-only query of Calibre-Web shelf metadata. It retrieves organizational/collection information with no side effects, no data modification, and no external execution. The low severity reflects minimal blast radius if misused—an AI agent listing shelves poses no risk to system integrity, financial assets, or data persistence.

From the tool's definition Tool name contains 'list' action pattern and description states 'List available shelves' — a query-only operation that retrieves data about bookshelves/collections without modification, deletion, or execution.

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

POLICY

How to control crow_calibreweb_shelves

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_calibreweb_shelves:

policy.json

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

crow_calibreweb_shelves 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.

CAP THIS TOOL →

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EXPLORE

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
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FAQ

Questions about crow_calibreweb_shelves

What does the crow_calibreweb_shelves tool do? +

List available shelves (bookshelves/collections) in Calibre-Web. 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_calibreweb_shelves? +

Register the Crow MCP server in PolicyLayer and add a rule for crow_calibreweb_shelves: 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_calibreweb_shelves? +

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

Can I rate-limit crow_calibreweb_shelves? +

Yes. Add a rate_limit block to the crow_calibreweb_shelves 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_calibreweb_shelves completely? +

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

crow_calibreweb_shelves 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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