Librarian MCP server

📚 librarian

Turn any ebook into clean, token-counted Markdown chapters — let Claude read your bookshelf over MCP and catch it misquoting your books. Deterministic RAG: no embeddings, no network, no API keys.

Any input format — FB2, EPUB, DOCX, HTML, TXT/MD, text-layer PDF — becomes a directory of clean chapters with token counts. No network, no LLM, no randomness: the same input always produces byte-identical output.

Install

uv tool install librarian-cli
# or: pipx install librarian-cli

Offline contract: install and runtime need no network (the tokenizer's vocabulary is vendored in the package).

Quick start

lib ingest examples/*.epub
lib list
lib find curiouser
lib get <book-id> --budget 3000

Commands

Command	Purpose
lib ingest <files…> [--force] [--no-keep-source] [--config cfg.toml] [--verbose]	Process books into the library; prints a file · id · status · score table.
lib list [<book-id>]	No argument — all books; with an id — that book's chapters (n, title, tokens, summary).
lib get <book-id> <spec>	Print chapters by range (1-3,7) to stdout.
lib get <book-id> --budget N [--from K]	Greedily print consecutive chapters from K while the token sum stays ≤ N.
lib find <query> [--limit 10] [--book <id>] [--reindex] [--json]	Full-text search across chapters and titles/authors library-wide (bm25, snippets, RU/EN stemming).
lib info <book-id>	JSON: book metadata + quality metrics.
lib doctor [<book-id>]	No id — books in review and broken directories; with id — that book's report.
lib reingest --all [--config cfg.toml] [--verbose]	Rebuild the library from source/ with the current code/config.
lib rm <book-id>	Delete a book and rebuild the index.
lib serve [--library <path>]	Stdio MCP server over the library.
lib verify "quote" [--book ID] [--json] [--limit N]	Check a quote against one book or attribute it across the library.

Library root: --library <path> (or the LIB_HOME env var, default ./library). Data goes to stdout, diagnostics to stderr. Exit codes: 0 success, 1 runtime error, 2 usage error.

Give Claude your bookshelf

librarian-cli ships a built-in stdio MCP server with 6 read-only tools — list_books, list_chapters, find, get_chapters, book_info, verify_quote — so Claude can browse the catalog, search it, pull chapters under a token budget, and check its own quotes against the source on its own: deterministic RAG with no embeddings, no network, and no API keys.

Claude Code:

claude mcp add librarian --env LIB_HOME=$HOME/books -- uvx librarian-cli

Claude Desktop (claude_desktop_config.json):

{
  "mcpServers": {
    "librarian": {
      "command": "uvx",
      "args": ["librarian-cli"],
      "env": { "LIB_HOME": "/path/to/books" }
    }
  }
}

Verify quotes

An MCP server that catches Claude misquoting your books.

lib verify "quote" checks whether a quote actually appears in your library, verbatim — punctuation, case, ё/е, and markdown formatting don't count. Two modes:

• Book mode (--book <id>): full scan of one book — "does this book actually say this?" Works without the search index.
• Shelf mode (no --book): attribution across the whole library via FTS5 candidates — "which book is this from?" The quote needs at least 5 significant words (stop words don't count), or the check is skipped with verdict: null.

lib verify "Рукописи не горят" --book bulgakov-master-i-margarita
lib verify "рукописи не горят никогда"

verdict	meaning
exact	matches after normalization (punctuation/case/ё/typography don't count)
close	similarity ≥ 0.95 — near-exact, differences shown as a word-diff
distorted	similarity ≥ 0.75 — the right place, but the quote is misremembered
not_found	similarity < 0.75 — nothing like it in the book/library
null	check wasn't run: empty quote, or a short quote without --book

Exit codes (grep-style semantics, a deliberate departure from the project's usual "1 = runtime error" — see docs/MILESTONES.md deviation 38):

exit	case	stdout
0	exact / close — quote confirmed	full report / JSON
1	distorted / not_found — not confirmed	full report / JSON
1	runtime error (unknown book id, no search index, locked index)	empty
2	usage error: empty/short quote (verdict: null), --limit < 1	empty (message on stderr)

Script discriminator: exit 1 with non-empty stdout means "checked, not confirmed"; exit 1 with empty stdout means an error (diagnostics went to stderr instead). Exit 0 includes close — a strict CI gate must check verdict == "exact" in the --json output, not the exit code alone.

Quality

Every book gets a score from five metrics (coverage, structure, garbage, encoding, dehyphenation): ok (score ≥ 0.90, no hard triggers) — saved silently; review (0.60 ≤ score < 0.90, or triggers present) — saved with a warning, details via lib doctor <id>; failed (score < 0.60) — not saved. Scans and password-protected PDFs honestly fail (OCR and DRM removal are out of scope).

Determinism

The pipeline has no network access, no LLM calls, and no randomness — the same input file always produces byte-identical output. That makes ingestion reproducible and cacheable, and it's what makes lib serve's RAG deterministic: no embeddings to drift, no model calls to vary between runs.

Limitations

• PDF: works well on typographically normal books; complex layouts may land in review.
• DRM is not circumvented; source legality is the user's responsibility.
• Networked filesystems (NFS/SMB) are not supported (the advisory lock isn't reliable there).
• MOBI/DJVU and text-less scans are not supported (v3 candidates: OCR, calibre).
• CLI messages are currently in Russian; English output is planned.
• lib verify: quotes spanning a chapter boundary are not supported (v1) — the best you'll get is distorted on one half.
• lib verify: close on a single-word replacement is realistic from ~150 characters of quote; shorter quotes with a replaced word honestly land in distorted — a third of a three-word quote really is a distortion.
• lib verify shelf mode (no --book) needs the FTS5 search index; book mode (--book <id>) works without it in the CLI. lib serve as a whole still requires FTS5 — it syncs the index at startup regardless of which tool gets called.
• lib verify in book mode scans the whole chapter text in pure Python; a long book can take a few seconds of CPU. The MCP tool runs it in a worker thread so it doesn't block the rest of the server.

Русская версия

See README.ru.md for the Russian documentation.