convert_ebook

Convert an ebook from one format to another (e.g., EPUB to MOBI, PDF to EPUB). Automatically adds the new format to the book

SERVERCalibre SOURCE2b3pro/calibre-mcp

Medium RISK CLASS

Category Write

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade B, identity unverified Pull the record →

This record as markdown: /tools/2b3pro-calibre-mcp/convert-ebook.md

WHAT IT DOES

What convert_ebook does on Calibre

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

RISK

Why convert_ebook is rated Medium

This tool creates a new converted file and modifies the book's metadata/library by adding a new format. This is a reversible write operation—the converted file can be deleted and the metadata entry removed. It does not execute arbitrary code, delete data permanently, or move money.

From the tool's definition Tool description states it 'Convert[s] an ebook from one format to another' and 'Automatically adds the new format to the book', indicating creation of new data (the converted file) and modification of library state (adding a new format entry).

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs convert_ebook safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Calibre, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For convert_ebook, this is the rule to start with:

convert_ebook Rate-limited

convert_ebook 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": {
    "convert_ebook": {
      "limits": [
        {
          "counter": "convert_ebook_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Calibre, apply this rule, and every convert_ebook call is checked against it from then on.

FAQ

Questions about convert_ebook

What does the convert_ebook tool do? +

Convert an ebook from one format to another (e.g., EPUB to MOBI, PDF to EPUB). Automatically adds the new format to the book. It is categorised as a Write tool in the Calibre MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on convert_ebook? +

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

What risk level is convert_ebook? +

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

Can I rate-limit convert_ebook? +

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

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

convert_ebook is provided by the Calibre MCP server (2b3pro/calibre-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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