io.github.cyanheads/libofcongress-mcp-server

List and browse Library of Congress curated digital collections. Returns collection names, descriptions, item counts, slugs, and URLs. Optionally filter by keyword. Collections are curated subsets of the digital holdings with specific focuses (e.g., "Civil War Glass Negatives", "Baseball Cards", "WPA Posters"). Pass a returned slug to libofcongress_search_items.collection_slug to search within it; use query "*" to browse matching records, optionally with format, date and sort filters. Use the returned URL to navigate directly to a collection on loc.gov.

Retrieve the full metadata record for a specific LOC digital item. Returns the imprint (place, publisher, and date of publication), contributors, LCSH subject headings and the subject terms the search subject filter accepts, summary, languages, locations, rights information, physical description, call number, original and online formats, access restrictions, former catalog IDs, notes, and related items, plus the item's digital resources (each with its page count, representative image, PDF, and audio) and a window of its pages. Each page has a page_url and has_text; pass a page_url with has_text true to libofcongress_get_newspaper_page to read that page's text (newspaper, book, and manuscript pages alike). A long item lists 50 pages per call: continue with page_offset set to next_page_offset. Set include_files for each listed page's downloadable files (TIFF, JP2, JPEG sizes, text). Use after libofcongress_search_items on a result whose is_item is true. Pass the result id — a simple ID, an LCCN, or a slash-separated newspaper path — or a loc.gov item link (`https://www.loc.gov/item/<id>/`) or LCCN permalink (`https://lccn.loc.gov/<lccn>`), which is read as its id. Non-item results (is_item: false) — collections, exhibits, guides, newspaper pages, catalog.loc.gov records, hdl.loc.gov finding aids — have no item record and cannot be retrieved here.

Retrieve the full text of one LOC page — a historical newspaper page, or a book or manuscript page — or, with match, only the passages around your search terms, with its publication metadata: for newspapers the title, issue date, place of publication, indexed states, and edition; for every page its sequence, the page count, and the item_title and item_id of the issue, book, or manuscript it belongs to — pass item_id to libofcongress_get_item to list every page of the item. Pass the url field from a libofcongress_search_newspapers result, or a pages[].page_url from libofcongress_get_item (has_text true), or a Chronicling America page link (…/ed-N/seq-M/) — do not construct this URL manually. A dense newspaper page runs to 50,000 characters: to find the article a search hit on, pass the search query as match and read the passages around it rather than the whole page. The text is OCR, or for some manuscripts a volunteer transcription; OCR quality varies by digitization batch and era, and 19th-century and degraded materials may contain fragmented text, garbled words, and line-break artifacts that are surfaced as-is. When a page exists but has no digitized text, ocr_available is false and ocr_text is empty — this is a data property, not an error.

Search the Library of Congress digital collections by keyword. Optionally filter by material format (photos, maps, newspapers, audio, etc.), date range, subject heading, or geographic location, or scope the search to a single curated collection with collection_slug. Returns item summaries with titles, dates, descriptions, LOC IDs, and format tags. Each result carries is_item: pass the id of a result where is_item is true to libofcongress_get_item for full metadata. Non-item resources include collections, exhibit and research-guide pages, newspaper pages, catalog.loc.gov records, and hdl.loc.gov finding aids. When page_url is present, pass it to libofcongress_get_newspaper_page, optionally using the search query as match; its item_id identifies the issue. A link_notice warns that a retired catalog URL no longer opens its record; otherwise follow a non-item url. Use libofcongress_search_subjects to find an LCSH heading for the subject filter. To discover the subject and location values the filters accept for a search, set include_facets to get its top subject_facets and location_facets.

Search historical newspaper pages in the Chronicling America corpus. Returns matching pages with the opening of each page's OCR text (~500 characters), publication title, date, the states LOC indexes the title under, and the page URL needed for libofcongress_get_newspaper_page. Filters by keyword, date range, indexed state/province, and newspaper title. The excerpt is the page's first lines, not the text around the match: to read where the query occurs, call libofcongress_get_newspaper_page with the returned url field and this query as its match, which returns the passages around each occurrence; omit match for the full page text. OCR quality varies: 19th-century and degraded materials may contain fragmented or garbled text.

Search Library of Congress Subject Headings (LCSH) by keyword. Returns authorized subject headings and their URIs in a stable paged order, promoting an exact match from the first 50 results to the start; a partial word with no keyword match returns the headings that begin with it. Use the returned label as the subject filter in libofcongress_search_items — LCSH uses precise, standardized terms that differ from natural language (e.g., "World War, 1939-1945" not "World War II"; "Aerial photography" not "Photography, Aerial"). Running this tool before a subject-filtered libofcongress_search_items dramatically improves result quality.