mcp-refchecker

An MCP server that lets Claude verify academic citations in real time against Semantic Scholar, OpenAlex, and Crossref — catching hallucinated or incorrect references before they end up in your work.

Built on top of academic-refchecker (MIT).

Tool

verify_citation — verifies that a cited paper exists and that its metadata (title, authors, year, venue) matches what was cited.

Parameter	Type	Required	Description
title	string	yes	Title of the cited paper
authors	string[]	no	List of author names
year	integer	no	Publication year
doi	string	no	DOI (e.g. 10.1145/12345)
arxiv_id	string	no	arXiv ID (e.g. 2301.00001)
url	string	no	Direct URL to the paper

Returns JSON:

{
  "verified": true,
  "url": "https://...",
  "matched_paper": {
    "title": "...",
    "authors": [...],
    "year": 2023,
    "venue": "..."
  },
  "possible_match": null,
  "errors": null,
  "warnings": null,
  "info": null
}

Result fields

• verified — true if the paper was found and all provided metadata (year, authors, venue) matches. false if there is a real metadata conflict or the paper could not be found.
• matched_paper — the authoritative metadata from the verification source.
• possible_match — a Crossref fallback match when the exact title was not found but a close variant was (see "Fuzzy fallback" below).
• errors — hard errors that block verification (wrong year, wrong authors, paper not found).
• warnings — soft warnings that don't block verification (arXiv v1 vs v2 differences, arXiv preprint vs published venue, incomplete input metadata).
• info — informational suggestions (e.g., "reference could include arXiv URL").

What counts as an error vs a warning

academic-refchecker returns a flat list of issues with some inconsistency (year mismatches get marked as warnings while author mismatches get marked as errors). This wrapper normalises the output:

• Promoted to hard errors: plain year/author/venue mismatches where the cited metadata actually differs from reality. These block verified.
• Demoted to warnings: "missing field" errors when the paper was found but the user didn't provide that field in the first place. Missing input metadata is not evidence of a hallucinated citation.
• Kept as warnings: arXiv version differences (v1 vs v2), preprint-vs-published venue notes.

Fuzzy fallback and its limitations

When academic-refchecker reports that a paper could not be verified, this wrapper makes a secondary query to Crossref using fuzzy title matching and fuzzywuzzy.ratio. If a candidate with ≥ 85% similarity is found, it's returned as possible_match with a warning.

What the fuzzy fallback catches:

• Stylistic title variations (case differences, punctuation, word order)
• Minor rewording
• Titles where refchecker's strict comparison rejected an otherwise valid match

What the fuzzy fallback does NOT catch:

• Real typos in distinctive title words (e.g., "Atention Is All You Need")
• Heavily mangled titles

This is a fundamental limitation of free academic search APIs. Crossref, OpenAlex, and Semantic Scholar all do keyword/token-based search — as soon as a distinctive word is misspelled, it simply isn't in the search index, and the real paper won't appear in results regardless of how you post-process them. Catching real typos would require semantic embeddings from a paid API (OpenAI, Voyage, etc.) or a full-text fuzzy search engine, neither of which is exposed by free scholarly data sources.

If you suspect a typo but verify_citation returns unverified, the best workaround is to rewrite the title in the most canonical form you can and try again.

Installation

pip install mcp-refchecker

Or from source:

git clone https://github.com/JonasBaath/mcp-refchecker
cd mcp-refchecker
pip install .

Configuration

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "refchecker": {
      "command": "mcp-refchecker"
    }
  }
}

Optional environment variables

• SEMANTIC_SCHOLAR_API_KEY — apply for one here for higher rate limits on refchecker's primary verification path.
• CROSSREF_MAILTO — your contact email, used to opt into Crossref's polite pool for more reliable fuzzy fallback access.
• MCP_REFCHECKER_DEBUG — set to any non-empty value to print debug logging from the fuzzy fallback path to stderr.

Example with all optional settings:

{
  "mcpServers": {
    "refchecker": {
      "command": "mcp-refchecker",
      "env": {
        "SEMANTIC_SCHOLAR_API_KEY": "your-key-here",
        "CROSSREF_MAILTO": "[email protected]"
      }
    }
  }
}

License

MIT — © Jonas Bååth. Built on academic-refchecker (MIT).