Sru

An MCP server that searches library catalogs worldwide using the SRU (Search/Retrieve via URL) protocol. No API keys required — SRU is an open standard supported by national libraries, university catalogs, and consortia.

Features

• 5 tools for LLM-driven bibliographic search
• 7 pre-configured servers including Library of Congress, BnF, DNB, and more
• Parses MARCXML and Dublin Core record formats
• Supports any SRU-compliant server — pass a URL or use a built-in server ID
• Raw CQL queries or high-level field-based search (title, author, ISBN, subject, etc.)

Quick Start

Install

pip install mcp[cli] httpx xmltodict

Run

python server.py

Claude Desktop

Add to your Claude Desktop config (~/Library/Application Support/Claude/claude_desktop_config.json):

{
  "mcpServers": {
    "sru": {
      "command": "python",
      "args": ["/path/to/sru-mcp/server.py"]
    }
  }
}

Tools

Tool	Description
sru_list_servers	List all pre-configured library catalog servers
sru_explain	Get a server's capabilities, supported schemas, and indexes
sru_list_indexes	List available search indexes on a server
sru_search	Execute a raw CQL query
sru_search_books	Search by title, author, ISBN, subject, publisher, year, or keyword

Example Usage

Search the Library of Congress for books by Melville:

sru_search_books(server="loc", author="Melville", title="Moby Dick")

Search the French national library with a raw CQL query:

sru_search(server="bnf", cql_query='dc.title = "Les Misérables"')

Pre-configured Servers

ID	Name	Notes
loc	Library of Congress	US national catalog
loc-names	LC Name Authority	Personal and corporate names
loc-subjects	LC Subject Authority	Subject headings and genre terms
bnf	Bibliothèque nationale de France	French national library
dnb	Deutsche Nationalbibliothek	German national library
kb	Koninklijke Bibliotheek	Netherlands national library
bibsys	BIBSYS	Norwegian academic libraries

To add a server, edit servers.json.

Development

# Install dev dependencies
pip install pytest pytest-asyncio respx

# Run tests
python3 -m pytest test_sru.py test_server.py -v

# Test with MCP Inspector
npx @modelcontextprotocol/inspector python server.py

Project Structure

server.py       FastMCP server — tool definitions
sru.py          SRU protocol client — HTTP, parsing, formatting
servers.json    Server registry
test_sru.py     Tests for sru.py (92 tests total)
test_server.py  Tests for server.py

License

MIT