Openlibrary MCP Server

@cyanheads/openlibrary-mcp-server Search books and authors, fetch editions, browse subjects, and resolve cover images from Open Library via MCP. STDIO or Streamable HTTP. 10 Tools • 2 Catalog Resources • 1 Agent Skill

Public Hosted Server: https://openlibrary.caseyjhand.com/mcp

Overview

Open Library's catalog of 20M+ books, editions, authors, and subjects, plus full-text search inside Internet Archive's scanned books. Search and browse, drill from a work into its editions or an author into their works, and construct cover image URLs.

Tools

Resources

Both resources mirror data also available via openlibrary_get_work and openlibrary_get_author — useful for clients that don't surface MCP resources.

Agent skill

openlibrary-guide covers edition selection, bibliography resolution, passage identification, and incomplete metadata. It is included in npm, Docker, and desktop bundles and served through MCP skill discovery and skill:// resources.

Capability reference

Paginated tools return at most 100 rows per call. Larger positive integer limits are clamped with a notice showing the applied limit and next offset. OPENLIBRARY_CLAMP_LIMITS=false restores schema rejection above 100. Text and structured output carry the same complete domain data, including arrays and numeric precision.

openlibrary_search_books tool

• Free-text query with Solr field prefixes (title:, author:, subject:, publisher:, isbn:, language:) or dedicated filter parameters; 1–100 results per page (default 10), offset pagination
• sort: relevance (default), new, old, rating, editions
• language accepts a 3-letter MARC code or a translatable 2-letter ISO code; an untranslatable 2-letter code fails as unknown_language_code rather than being silently dropped
• include_availability adds live Internet Archive borrow/read status (~200ms latency), off by default; flags Open Library leaves out are omitted rather than reported as false, and availability: null means none was returned for the work
• Returns work-level records with edition counts, cover IDs, subjects, and Internet Archive identifiers
• Optional matching_edition and matching_edition_count preserve the Search API's selected edition and matching count. The selected edition is provider-ranked; it does not prove that every unfielded search term matches that edition
• invalid_search_query reports upstream HTTP 422 validation with recovery guidance; empty queries with specific filters remain supported

openlibrary_get_work tool

• Fetch by Open Library Work ID (OL…W), optionally /works/-prefixed; anything else — an ISBN, an edition or author OLID — fails input validation before any request, naming openlibrary_get_edition (id_type: "isbn") as the route from an ISBN to its work
• Returns title, description, subjects (plus place/time/people breakdowns), cover IDs, and author IDs — no author names (use openlibrary_get_author or openlibrary_search_books)
• A merged work ID stays reachable — the redirect chain is followed to the canonical record, work_id reports the canonical ID, and an enrichment notice names both IDs when they differ
• not_found when the Work ID doesn't exist or its redirect chain reaches no work

openlibrary_get_editions tool

• List editions of a work by Work ID (OL…W), optionally /works/-prefixed; 1–100 per page (default 10), offset pagination, with the requested offset echoed in the output
• Same work_id validation as openlibrary_get_work — an ISBN resolves to its work through openlibrary_get_edition (id_type: "isbn")
• Returns ISBN-10/13, publishers, languages, page count, cover IDs, and edition OLIDs (OL…M), plus physical_format and edition_name when recorded
• A merged work ID stays reachable — the editions of the canonical work come back under its ID in work_id, with an enrichment notice naming both IDs; a live work still costs one request
• not_found when the Work ID doesn't exist or its redirect chain reaches no work

openlibrary_get_edition tool

• Accepts 1–1,000 input strings, deduplicates exact strings, and processes the first 50 distinct identifiers in one upstream batch; the remainder is returned as unprocessed for resubmission. Every identifier shares one id_type: isbn (10 or 13 digits, an ISBN-10 may end in an X check digit), oclc (numeric), lccn (unchecked), or olid (OL…M). With OPENLIBRARY_CLAMP_LIMITS=false, the input array is limited to 50 entries
• Partial success: identifiers that resolve return in editions (request order); the rest land in unresolved with invalid_identifier (malformed, never sent upstream) or not_found (well-formed, no record) — the call fails only when nothing resolves
• upstream_unavailable (retryable) when Open Library's batch lookup itself fails — an HTTP error status other than a rate limit, or an HTML page — so an upstream outage never reads as a missing edition
• Authors come inline — the edition's own credits, or ones marked source: "work" recovered from the parent work when the edition itself lists none; if those lookups fail, the batch still returns, and an enrichment notice names the editions whose authors are missing or shown by ID
• Returns ISBN-10/13, OCLC, LCCN, LC call numbers, publishers, all cataloged languages, page count, cover IDs, parent work ID, and an Internet Archive ebook_url when one exists. The singular language remains the first cataloged language; physical_format and edition_name preserve the catalog's wording when present
• If no processed identifier resolves, the existing typed error also carries every unprocessed identifier in its data and recovery hint

openlibrary_search_authors tool

• Search by name — partial and alternate names match; 1–100 per page (default 10), offset pagination
• Returns Author ID (OL…A), alternate names, birth/death dates, top work, work count, top subjects, and average rating

openlibrary_get_author tool

• Fetch by Author ID (OL…A); a leading /authors/ prefix is stripped
• Returns bio, birth/death dates, photo IDs, and linked identifiers (Wikidata, VIAF, ISNI, Goodreads, LibraryThing)
• A merged author ID stays reachable — the response is the canonical record, and an enrichment notice names the canonical ID when it differs from the one requested
• not_found when the Author ID doesn't exist, names a record that is not an author (a work or edition OLID), or its redirect chain reaches no author

openlibrary_get_author_works tool

• List works by Author ID (OL…A); 1–100 per page (default 20), offset pagination, with the requested offset echoed in the output
• Returns title, first-publish date, cover IDs, and Work ID (OL…W) per work
• A merged author ID stays reachable — an enrichment notice names the canonical ID when it differs from the one requested
• not_found when the Author ID doesn't exist, names a record that is not an author (a work or edition OLID), or its redirect chain reaches no author

openlibrary_get_subject tool

• Subject name is trimmed, lowercased, and normalized from whitespace to underscores; 1–100 per page (default 12), offset pagination, with the requested offset echoed in the output
• Blank input fails as invalid_subject before any request
• Returns canonical subject name, normalized subject key, total work count, and per-work author names, edition count, and cover ID
• Empty results carry a recovery notice suggesting a different word form, synonym, or broader term — subject tags are user-contributed and inconsistent

openlibrary_search_inside tool

• Full-text search across Internet Archive's scanned book text — the only tool that answers "which book contains this passage?"; quot