MCP Libraryofcongress

mcp-libraryofcongress

The Library of Congress is the national library of the United States, and it publishes a large part of its holdings online: books, photographs, maps, sound recordings, manuscripts, and the pages of American newspapers going back to the eighteenth century. The newspaper pages have been scanned and run through optical character recognition, so the words printed on them can be searched. Curators also gather material into digital collections, each described and published as a body of its own.

This server connects a chat client to that library. You can search the words printed inside the newspapers, search the catalogue by title, creator, subject, place or language, read one record with its rights statement and where the original is held, and list the digital collections. It needs no API key and no account.

_Version française_

Install

One-click install

Claude Code

claude mcp add libraryofcongress -- npx -y mcp-libraryofcongress

Claude Desktop, Cursor, and any client using the standard config format

{

"mcpServers": { "libraryofcongress": { "command": "npx", "args": ["-y", "mcp-libraryofcongress"] } } }

Node 24 or later is required, and no environment variable has to be set.

With Docker

{

"mcpServers": { "libraryofcongress": { "command": "docker", "args": ["run", "-i", "--rm", "ghcr.io/smeet666/mcp-libraryofcongress:3.1.0"] } } }

-i keeps stdin open, which is where the protocol travels, and -t is left out because a TTY rewrites the stream. The container needs outbound HTTPS to www.loc.gov and chroniclingamerica.loc.gov, and nothing else: no volume, no port, no credential.

Bundle, without npm

Download mcp-libraryofcongress-3.1.0.mcpb from the latest release and open it. A client that supports MCP bundles installs it on its own, with no npm and no configuration file to edit. The bundle carries its dependencies, so nothing is fetched at install time.

What you can ask

• "What did Oklahoma newspapers write about the 1907 statehood vote?"
• "Find me photographs of Chicago tenements before 1920."
• "Read that record and tell me who holds the original."
• "What digital collections are there on the Civil War?"
• "Can I reuse that photograph?"

The ordinary path runs from a search to a record: a row carries an identifier, and get_item reads it.

Tools

search_newspapers

Searches the text of scanned newspaper pages, which came off the page through optical character recognition.

In return: hits, each carrying identifier, which get_item takes; title; creator, which is the library that contributed the scan; year; page_number, the leaf within the issue; published_on; publication with the years the paper ran; state; excerpts; and excerpt_kind.

`excerpt_kind` decides what an excerpt is worth. A passage is the text around the words that matched, centred on them. A page_opening is the start of the leaf, sent because the text the Library returned with the row stops before those words appear: it does not carry the match, so quoting it quotes something else, and source_url opens the leaf with the query applied. `total` counts newspaper leaves, and it pages: it is never a count of how many times the words occur.

search_items

Searches the catalogue, one kind of thing at a time.

In return: items, each carrying identifier, title, creator, year, date as published, which is often a range, is_collection and source_url. The Library keeps one catalogue per kind of thing, so a search without media_type reads the general one, and total counts the records matching there.

get_item

Reads one record. The heavier parts are asked for rather than served by default, and a long description paginates.

In return: the record with its title, creator, year, date, format and source_url, plus description, subjects, location, language, part_of for the collections and divisions it sits in, repository naming where the original is held, call_number and rights. A field the record leaves empty is null. next_offset continues a long description and is null at the end. An identifier can carry slashes: a single newspaper issue is named by its paper, its date and its edition together.

list_collections

Lists the digital collections, bodies of material a curator chose, described and published together.

| limit | integer, 1 to 50, default 20 | n