Citation Checker in VS Code

Questions it 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 or "has this paper been retracted?".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It also reports whether a paper has been retracted, partially retracted, flagged with an expression of concern or corrected, from the notices that publishers and the Retraction Watch database register with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.

Short questions this server answers, each with a direct answer: Check references and DOIs for real papers.

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 or "has this paper been retracted?".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 VS Code

VS Code reads MCP servers from mcp.json and offers their tools to Copilot Chat in Agent mode. A workspace file at .vscode/mcp.json applies to that project. For every workspace, run MCP: Open User Configuration from the Command Palette and add the same entry there. These steps were checked against the VS Code MCP servers guide on 2026-10-09.

Create or edit the file so it contains this server. VS Code uses a top-level servers object, not mcpServers. Merge it with servers you already have.

{
  "servers": {
    "citations": {
      "type": "http",
      "url": "https://citations.openkrill.app/mcp"
    }
  }
}

No command, no headers and no input variables for a key: Citation Checker answers without a login. Save the file and select Start above the entry. VS Code asks once whether you trust the server: confirm it. Run MCP: List Servers to check that Citation Checker is running. You should see check_references.

Open the Chat view, choose Agent mode and ask: Check my bibliography and tell me which references are real The Configure Tools button in the chat input lists the tools of each server, and VS Code may ask you to confirm the first call. The server is public and read-only. It sees only the arguments of each call, so do not paste secrets into the question.

Command line users can add it to the user profile in one step with code --add-mcp and the same name, type and url as JSON. The portable .mcp.json at the project root also works in VS Code, with mcpServers as its top-level key. An organization can turn MCP off through Copilot policy: if the MCP commands are missing, ask the admin.

If it does not work

A call checked on 2026-10-17

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 2026-10-17.

{
  "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.

Using it in production

Nothing to install and nothing to run: no package, no Python or Node.js version and no environment variable. Citation Checker runs on our servers, and your client only needs the URL https://citations.openkrill.app/mcp.

Use it in other apps

• Citation Checker in ChatGPT
• Citation Checker in Claude
• Citation Checker in Cursor
• Citation Checker in Pi

Roles that use Citation Checker

• Researcher guide

Frequently asked questions

Words on this page

• MCP (Model Context Protocol) definition
• Streamable HTTP transport definition
• Tool primitive definition
• Rate limit policy definition

Source: plugin listing for citations in this repository, and a live tools/call on 2026-10-17. As of 2026-10-17.