Crossref MCP server

Crossref — DOI Metadata

Crossref is the largest DOI (Digital Object Identifier) registration agency. Every DOI you've seen in an academic citation goes through them. Their API exposes structured metadata for ~150M+ scholarly works: titles, authors, ORCIDs, abstracts where available, references, citation graphs. Free, no auth required.

Part of Pipeworx — an MCP gateway connecting AI agents to 1679+ live data sources.

Why this matters for AI agents

Where Semantic Scholar is search-focused, Crossref is the authoritative source for DOI metadata. If you have a DOI and need its canonical metadata, Crossref is the answer. Citation networks are also more complete here than in many discipline-specific databases.

Common flows:

• DOI → metadata. crossrefgetwork({doi: "10.48550/arXiv.1706.03762"}) → title, authors, journal, year, citations.
• Author DOIs. Find a researcher's published works by ORCID or name.
• Citation graph. A paper's references and which papers cite it (where reported).

For free-text academic search, prefer Semantic Scholar — Crossref's search is more limited.

Citable URI: pipeworx://crossref/work/{doi}.

Auth

Public, free. Crossref has a "polite pool" giving priority to clients that identify themselves via User-Agent. Pipeworx forwards pipeworx-mcp/1.0 (https://pipeworx.io) so we get polite-pool treatment by default.

What's in a Crossref record

Common pitfalls

• Reference-list completeness. Some publishers send their full reference list to Crossref; others don't. A paper with 0 references in Crossref may have 50 in print. For exhaustive citation graphs, cross-reference with Semantic Scholar.
• Errata and retractions. Crossref tracks "scholix" links between original and retraction notices. Always check the relation field for is-retracted-by before citing.
• Author ORCID coverage. ORCID adoption has grown but isn't universal. Older papers and small-publisher works often lack ORCIDs. Don't rely on ORCID-based deduplication for full coverage.
• DOI normalization. Different sources format DOIs slightly differently: 10.1234/xyz, https://doi.org/10.1234/xyz, doi:10.1234/xyz. Crossref accepts the bare form. Strip prefixes before passing to the API.
• Books and chapters. Crossref covers books and chapters as well as articles. The type field tells you which (journal-article, book-chapter, proceedings-article, etc.). For systematic literature reviews, type filtering matters.
• Pre-prints. Some pre-print servers register DOIs through Crossref (arXiv, bioRxiv). The same content may have multiple DOIs (pre-print + accepted version). Track via relation field.

Quick Start

Add to your MCP client (Claude Desktop, Cursor, Windsurf, etc.):

{
  "mcpServers": {
    "crossref": {
      "url": "https://gateway.pipeworx.io/crossref/mcp"
    }
  }
}

What this endpoint actually serves

tools/list at https://gateway.pipeworx.io/crossref/mcp returns the tools in the table above plus the shared Pipeworx meta-tools — askpipeworx, discovertools, search_within, remember/recall and the rest of the gateway-wide set. So the tool count you see is larger than this table: a single-pack endpoint currently lists roughly 30 shared tools alongside the pack's own. The connection's initialize response states its exact scope, and is the authoritative answer for a given day.

Shortened. The full README is on GitHub.