Citation Checker in Pi
Check references and DOIs. The MCP server is https://citations.openkrill.app/mcp. No key. The steps below are only for Pi. A call to check_references was checked against that server on 2026-10-01.
What this server answers
Paste a bibliography or a single reference and find out whether the papers are real. Ask "are these references real?", "check my bibliography", "verify this citation", "is this DOI correct?" or "has this paper been retracted?".
Citation Checker looks every reference up in Crossref, the DOI system (doi.org) and OpenAlex, which index the scholarly record, and gives each one a clear verdict: found, mismatch or not found.
A mismatch means a real paper exists but the reference gets something wrong, such as a DOI that belongs to another paper or a wrong year or author list; the real record is shown so the error is easy to fix. Not found means nothing matching exists, which for a bibliography entry often points to an invented or garbled citation.
It also reports whether a paper has been retracted, partially retracted, flagged with an expression of concern or corrected, from the notices that publishers and the Retraction Watch database register with Crossref.
It checks up to 10 references at a time. It compares bibliographic details only (title, authors, year, journal, DOI); it does not read papers or judge whether their claims are true. Books, reports, web pages and talks are often missing from the scholarly indexes, so a not found there is a prompt to check by hand, not proof.
It stores nothing about you: answers are cached for up to six hours, and the only lasting record is a daily count of calls per tool.
What it can do
- Checks whether the references in a bibliography are real papers
- Flags a DOI that belongs to a different paper than the reference describes
- Finds a wrong year or author list by comparing a reference with the real record
- Reports retractions, expressions of concern and corrections for a paper
- Looks up references that have no DOI by their title, authors and year
Tools
check_references, Check references and DOIs. Use this when the user asks "are these references real?", "check my bibliography", "verify this citation", "is this DOI correct?" or "has this paper been retracted?". Pass each reference as one string as written (authors, year, title, journal, DOI), or just a DOI or a title, up to 10 at a time. Looks each one up in Crossref, the DOI system and OpenAlex and returns a verdict per reference: found (a real record matches), mismatch (a real record exists but the DOI, title, authors or year differ; the real record is shown) or not_found (nothing matches, so it may be invented or garbled). Also returns the paper's retraction status (retracted, expression of concern, corrected) from Crossref. It checks bibliographic details only, not whether a paper's claims are true.
Add Citation Checker in Pi
Pi does not speak MCP on its own. The pi-mcp-adapter extension (these steps match version 2.34.0) loads remote servers and keeps their schemas out of the prompt until you ask. Install it once, then restart Pi:
pi install npm:pi-mcp-adapterAdd the server to a shared MCP file. Use .mcp.json in the project if only that project needs Citation Checker, or ~/.config/mcp/mcp.json if you want it in every project. Pi also reads ~/.agents/mcp.json. A Pi-only override lives in ~/.pi/agent/mcp.json or .pi/mcp.json and wins over the shared file.
{
"mcpServers": {
"citations": {
"url": "https://citations.openkrill.app/mcp"
}
}
}The url is enough. Do not set command: that field is for a local process. No API key header. After restart, run /mcp and confirm the server is listed. The first call connects lazily. Ask: Check my bibliography and tell me which references are real The adapter should offer check_references.
Leave directTools off unless you want those schemas in every turn. With a handful of tools the cost is small. The default proxy is the better fit: search for the tool, then call it. /mcp disable citations writes a project override in .pi/mcp.json without editing the shared file. Run /reload after that change.
Pi will not find this server by scanning Cursor or Claude config unless you run /mcp setup and import it. Putting the url in .mcp.json is the direct path and the one this page tests against. The server is the same public endpoint the other clients use, with the same limits and the same privacy rules.
A call checked on 2026-10-01
A bare DOI is a valid reference string. The record is public in Crossref. The request below was posted to https://citations.openkrill.app/mcp as tools/call. HTTP 200. Source: the Citation Checker server, read 2026-10-01.
{
"method": "tools/call",
"params": {
"name": "check_references",
"arguments": {
"references": [
"10.1038/nature14539"
]
}
}
}- references. 1 returned
- references title. Deep learning
- references verdict. found
Repeat the call yourself if you need a newer reading. Cached answers expire. A rate limit is not a result: wait and try again. Nothing in the call is a ranking, a filing, or advice.