CrossRef MCP Server

An MCP (Model Context Protocol) server for searching and retrieving scholarly metadata from the CrossRef REST API — 150M+ records across all publishers and disciplines.

Built with FastMCP. No API key required.

Tools

Related MCP server: paper-search-mcp

Setup

1. Install

cd crossref-mcp-server
python3 -m venv venv
source venv/bin/activate
pip install -r requirements.txt

2. Configure environment (optional)

CrossRef doesn't require an API key, but setting a mailto address gives you access to their faster "polite" API pool:

cp .env.example .env
# Edit .env with your email address

3. Add to Claude Desktop

Add this to your claude_desktop_config.json:

{
  "mcpServers": {
    "crossref": {
      "command": "/path/to/crossref-mcp-server/venv/bin/python",
      "args": ["/path/to/crossref-mcp-server/server.py"],
      "env": {
        "CROSSREF_MAILTO": "your.email@example.com"
      }
    }
  }
}

Or if using Claude Code CLI:

claude mcp add crossref \
  /path/to/crossref-mcp-server/venv/bin/python \
  /path/to/crossref-mcp-server/server.py \
  -e CROSSREF_MAILTO=your.email@example.com

Usage examples

Once connected, you can ask Claude things like:

• "Search CrossRef for recent papers on transformer architectures"

• "Find works by Jane Smith on educational psychology from 2020-2024"

• "Look up the metadata for DOI 10.1038/nature14539"

• "Search for journals about machine learning"

• "Get the reference list for this paper and export as RIS for Zotero"

License

MIT