create_book_from_url · Lyceum MCP: Risk & Policy

WHAT IT DOES

What create_book_from_url does on Lyceum

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

WHY IT NEEDS A POLICY

Why create_book_from_url needs a policy

The tool performs a reversible write operation: it fetches external content and creates a new book entry in the Calibre library. While this adds data, it does not delete or overwrite existing data irreversibly, nor does it execute arbitrary code or perform financial transactions.

From the tool's definition Tool description states 'create an epub book from the article content, adding it to the library' — this creates new data (a book object) and persists it in the library.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

create_book_from_url Rate-limited

create_book_from_url 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": {
    "create_book_from_url": {
      "limits": [
        {
          "counter": "create_book_from_url_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 Lyceum, so you can run agents against it safely.

FAQ

Questions about create_book_from_url

What does the create_book_from_url tool do? +

Fetch a URL and create an epub book from the article content, adding it to the library. It is categorised as a Write tool in the Lyceum MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on create_book_from_url? +

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

What risk level is create_book_from_url? +

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

Can I rate-limit create_book_from_url? +

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

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

create_book_from_url is provided by the Lyceum MCP server (matthewp/lyceum). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.