Calibre Manager

An MCP server to manage and organize a Calibre library from an AI assistant (Claude Desktop, Cursor, etc.).

Unlike other Calibre MCPs —which are read-only— this one is built to write and inject metadata and keep your library spotless: tags, authors, series, covers, duplicates, conversion to AZW3 for Kindle, and more.

All writing goes through the official calibredb command, which is the supported, safe way to modify the library: it never touches metadata.db directly, avoiding corruption and conflicts.

Tools

Tool	What it does
health_check	Verifies that calibredb and the library respond.
search_books	Searches using Calibre syntax (tag:, author:, series:...).
get_book_metadata	Returns all metadata for a book.
list_categories	Lists a category's values with counts (tags, authors...).
library_stats	Total books and breakdown by category.
set_metadata	Sets (replaces) a book's fields.
add_tags	Adds tags without removing the existing ones.
remove_tags	Removes specific tags, keeping the rest.
rename_tag	Renames a tag across the whole library.
bulk_set_metadata	Applies metadata to every book matching a search.
add_book	Adds a file (EPUB/PDF/MOBI/AZW3...) to the library.
remove_books	Removes books by id (requires confirmation).
convert_book	Converts to another format (e.g. AZW3) and adds it to the book.
export_books	Exports books to a folder (e.g. for your Kindle).
find_duplicates	Detects duplicates by (title, author).
find_books_missing_metadata	Lists books without tags/cover/series/etc.
fetch_online_metadata	Fetches online metadata (Google Books...) and applies it.

Requirements

• Calibre installed (includes calibredb, ebook-convert and fetch-ebook-metadata).
• Node.js 18 or newer.

Installation

git clone https://github.com/ericknavarro/calibre-manager-mcp.git
cd calibre-manager-mcp
npm install      # installs dependencies and builds (the "prepare" script)

To rebuild after a change:

npm run build

The compiled server lives at dist/index.js.

Configuration in Claude Desktop

Edit claude_desktop_config.json (on Windows: %APPDATA%\Claude\claude_desktop_config.json) and add:

{
  "mcpServers": {
    "calibre-manager": {
      "command": "node",
      "args": ["C:\\Users\\<your-username>\\repos\\calibre-manager-mcp\\dist\\index.js"],
      "env": {
        "CALIBRE_LIBRARY_PATH": "C:\\Users\\<your-username>\\calibre",
        "CALIBREDB_PATH": "C:\\Program Files\\Calibre2\\calibredb.exe",
        "EBOOK_CONVERT_PATH": "C:\\Program Files\\Calibre2\\ebook-convert.exe",
        "FETCH_EBOOK_METADATA_PATH": "C:\\Program Files\\Calibre2\\fetch-ebook-metadata.exe"
      }
    }
  }
}

Restart Claude Desktop. To check it works, ask it: "Run a health_check on Calibre".

Where is my library?

It's the folder that contains metadata.db (in Calibre: top-right, over the library name → "Switch/create library" shows the path). If you omit it, Calibre's default library is used.

Environment variables

Variable	Required	Description
CALIBRE_LIBRARY_PATH	No	Path to the library, or Content Server URL. If omitted, the default.
CALIBREDB_PATH	No	Path to calibredb (defaults to looking it up on PATH).
EBOOK_CONVERT_PATH	No	Path to ebook-convert.
FETCH_EBOOK_METADATA_PATH	No	Path to fetch-ebook-metadata.
CALIBRE_USERNAME / CALIBRE_PASSWORD	No	Only if you use the Content Server via URL.

Important note: library locking

While the Calibre app is open using that same library, calibredb cannot open it — for reading or writing — because the app holds a lock (you get an error like "Another calibre program is running"). You have two options:

1. Close Calibre before write operations. (simplest)
2. Start Calibre's Content Server and point CALIBRE_LIBRARY_PATH at its URL (http://localhost:8080#library) with a username/password.

In short: keep Calibre closed while you use this MCP, or run the Content Server (which lets multiple programs share the library safely).

Usage examples

Once configured, you can ask Claude things like:

• "Tag book 5 with Philosophy and Stoicism without removing its tags."
• "Set the series 'Greek Classics' on all books by Plato and Aristotle."
• "Find duplicates in my library."
• "Which books have no cover?"
• "Convert book 12 to AZW3 for my Kindle."
• "Fetch the online metadata for 'The Name of the Rose' by Umberto Eco and apply it to book 8."

License

MIT © Erick Navarro