Evidentia

Evidentia

Catch AI-fabricated medical citations before you publish.

AIが捏造した医学引用を、公開前に捕まえる。

The evidentia command verifies every citation in a piece of medical writing against CrossRef, PubMed, OpenAlex, arXiv, and ClinicalTrials.gov and grades each one in a 4-tier classification. The companion agent skill adds a full 15-criteria evidence appraisal on top. Built by a board-certified pediatrician.

[](https://www.npmjs.com/package/evidentia) [](https://github.com/kgraph57/evidentia/actions/workflows/ci.yml) [](LICENSE) [](https://code.claude.com/docs/en/skills) [](https://code.claude.com/docs/en/skills)

[](README.md) [](README.ja.md)

📖 日本語で読む方は [日本語版 README → README.ja.md](README.ja.md) へ

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> Why now: A Lancet audit of 2.5 million biomedical papers (Topaz et al., May 2026; doi:10.1016/S0140-6736(26)00603-300603-3/fulltext)) found that 1 in 277 papers published in early 2026 contained a fabricated reference — up from 1 in 2,828 in 2023, a 12-fold rise that tracks the spread of AI writing tools. (The audit screened the PubMed Central open-access subset.) Coverage: STAT · Nature · Columbia Nursing · Retraction Watch. > > A fabricated DOI looks exactly like a real one. Evidentia is the open-source tool that resolves each one and tells you which is which.

> ⚕️ Scope: Evidentia is a pre-publication aid for writers, editors, and researchers — not clinical decision support. It does not diagnose, treat, or replace professional medical judgment.

30-second start

As a command-line tool (no install, no API key):

npx evidentia check your-article.md

As a Claude Code skill (full 15-criteria appraisal):

/plugin marketplace add kgraph57/evidentia
/plugin install evidentia@evidentia

Then just say: "Fact-check this article" / 「この記事をファクトチェックして」.

As a Codex Desktop plugin:

Marketplace source: https://github.com/kgraph57/evidentia.git
Plugin: evidentia

What it catches

Here is Evidentia run on a real AI-generated answer about vitamin D and childhood infections — four citations, formatted perfectly, all plausible:

$ npx evidentia check examples/inputs/ai-generated-answer.md

Evidentia: 4 citations — 1 verified, 1 mismatch, 2 hallucinated (75.0% fabrication rate)
  [OK ] doi:10.1136/bmj.i6583       — Paper exists and the cited metadata matches the registry record.
  [HAL] doi:10.1056/nejmoa2105512   — DOI does not resolve in CrossRef or OpenAlex, and no matching paper was found.
  [HAL] pmid:18768876               — Identifier resolves to a different paper ("Trafficking of antigen-specific
                                       CD8+ T lymphocytes…") than the one cited.
  [MIS] doi:10.1002/14651858.cd012734 — Paper exists, but cited metadata disagrees with the record (year).

One citation was real. One DOI was invented. One PMID pointed to an unrelated paper. One had the wrong year. A human reviewer would have to check all four by hand. Evidentia did it in seconds. See the [full report](examples/reports/ai-generated-answer.report.md).

> This is a deliberately tough example. Most carefully written articles score far lower — Evidentia's value is catching the handful that slip through, every time, without fatigue.

The 4-tier classification

Most "citation checkers" stop at "could not verify." Evidentia keeps going — it resolves the identifier and tells you why a citation is suspect:

| Tier | Verdict | Meaning | |:----:|---------|---------| | ✅ 1 | Verified | The paper exists and the cited title/authors/year/journal match the registry record. | | ⚠️ 3 | Bibliographic mismatch | A real paper exists, but the DOI/PMID is wrong, or the metadata disagrees (a real source cited carelessly — or a fabricated identifier bolted onto a real title). | | ❌ 4 | Hallucination | The identifier resolves to nothing, or resolves to a completely different paper. This is the signature of AI-generated text. | | 🔍 2 | Content review needed | The paper is real, but whether it's used in the right context needs a human or an LLM. Handled by the Evidentia skill, below. |

Two layers: deterministic engine + LLM appraisal

Evidentia is deliberately split into a part a computer can do perfectly and a part that needs judgment:

1. The engine (CLI + MCP server) — pure, deterministic citation verification. No API key, no LLM, no hallucination of its own. It answers one question with certainty: does this cited paper actually exist, and does the identifier point to it? Use it in a terminal, in CI, or as an MCP tool inside any agent.

2. The skill (Claude Code) — wraps the engine in a full 15-criteria critical-appraisal rubric: evidence level, statistical interpretation (relative vs. absolute risk, NNT), causation vs. correlation, conflicts of interest, exaggeration, population fit, ethics, and more — producing an A–F report with concrete fixes. This is the Tier-2 "is it used correctly?" layer the engine can't do alone.

You can use either on its own. Together they cover citation existence (deterministic) and citation honesty (appraisal).

Use it as an MCP tool

Give any agent the ability to verify citations:

claude mcp add evidentia -- npx -y evidentia-mcp

The server exposes one tool, verify_citations(text), returning the tiered report as Markdown or JSON. JSON responses include both the public 4-tier verdict and a machine-readable lookupVerified / resolverOutcomes trace for agents and CI.

Use it in CI

Block a pull request that introduces a fabricated citation. Drop [.github/workflows/evidentia.yml](examples/ci/evidentia.yml) into any medical-content repo:

- run: npx evidentia check content/**/*.md --fail-on-fabrication

--fail-on-fabrication exits non-zero if any citation is a mismatch or hallucination.

The 15-criteria skill (Claude Code)

When invoked as a skill, Evidentia evaluates medical content across 15 dimensions and adapts to the media type — research paper, news article, social post, patient leaflet, conference slide, guideline, pharma marketing, or AI-generated text.

The 15 criteria

1. Evidence level & study design
2. Citation & source accuracy (powered by the engine above)
3. Statistical interpretation
4. Causation vs. correlation
5. Bias & conflicts of interest
6. Exaggeration & overclaiming
7. Target population fit
8. Temporal validity
9. Jargon–readability balance
10. Ethical considerations
11. Logical consistency
12. Images & figures
13. Alternative explanations
14. Clinical relevance
15. Information completeness

Each item is rated Excellent / Good / Fair / Poor, aggregated into an overall A–F score with a public-health risk level (LOW / MEDIUM / HIGH). See [skills/medical-fact-check/SKILL.md](skills/medical-fact-check/SKILL.md).

Works with your agent

The skill follows the open Agent Skills SKILL.md standard, so it loads in Claude Code today and in any agent that adopts the format. The engine is a plain npm package and an MCP server — usable from Claude Code, Codex CLI, Cursor, or your own scripts.

Install

CLI

# one-off, no install
npx evidentia check article.md

# or install globally
npm install -g evidentia
evidentia check article.md --format md --out report.md

evidentia check    Verify citations in a file, web page, or stdin
  --format       Output format (default: text)
  --out                  Write the report to a file
  --mailto              Contact email for the CrossRef/OpenAlex polite pool
  --cache                Reuse registry HTTP responses from a local JSON cache
  --fail-on-fabrication        Exit 1 if any citation is mismatch/hallucination (CI)
  --offline                    Extraction only, no network

Claude Code skill / plugin

/plugin marketplace add kgraph57/evidentia
/plugin install evidentia@evidentia

Or copy the skill manually:

git clone https://github.com/kgraph57/evidentia.git
cp -r evidentia/skills/medical-fact-check ~/.claude/skills/

How verification works

For each citation, Evidentia extracts every identifier (DOI, PMID, arXiv, NCT trial ID, ISBN) and any nearby title/author/year, then:

1. Resolves the DOI against CrossRef, falling back to OpenAlex.
2. Resolves the PMID against PubMed E-utilities.
3. Resolves arXiv IDs against the arXiv API.
4. Resolves NCT trial IDs against ClinicalTrials.gov.
5. If the identifier doesn't resolve, searches by title in OpenAlex — this is how it distinguishes "real paper, wrong DOI" (Tier 3) from "this paper does not exist" (Tier 4).
6. Compares the cited title/authors/year against the registry record to catch an identifier that silently points to a different paper.

Each JSON citation also includes lookupVerified (true, false, or unresolvable) and resolverOutcomes (matched, unmatched, unreachable, or skipped, with whether the lookup was keyed by an identifier or a title). This keeps agent workflows auditable without changing the human-facing 4-tier verdict.

It is deliberately careful about **what it does not flag**: a book (ISBN), a clinical guideline, or any source that isn't indexed in these registries is marked "verify manually" (Tier 2), never "hallucination" — only a failing DOI/PMID/arXiv/NCT identifier (which is supposed to resolve) earns a fabrication verdict. Identifier-less entries in a reference list are surfaced for review rather than silently skipped.

All registries are free and keyless. Pass --mailto to join the faster "polite pool."

Examples

| Input | Result | |-------|--------| | [AI-generated answer](examples/inputs/ai-generated-answer.md) (real + fabricated mix) | [75% fabrication rate](examples/reports/ai-generated-answer.report.md) | | [Clean reference list](examples/inputs/clean-references.md) (all real) | [0% — all verified](examples/reports/clean-references.report.md) |

Limitations

• The engine verifies citation existence and bibliographic accuracy — not whether a real paper is summarized correctly. That semantic check is the skill's job (Tier 2), and even then it relies on what's publicly indexed (abstracts, open-access full text, metadata).
• This is decision support for writers, editors, and researchers — not clinical decision support. It does not diagnose, treat, or replace professional medical judgment.
• Very new papers may not yet be indexed, which can surface as a false "unverified." Re-run later, or pass --mailto for the freshest index.

Roadmap

• [x] Batch input — evidentia check a.md b.md … with an aggregate report ([benchmark: 22 cases](benchmark/))
• [x] arXiv ID verification, resolver traces, and optional local lookup cache
• [ ] evidentia-bench — grow to 100+ cases and publish per-model fabrication rates
• [ ] CrossRef/OpenAlex abstract retrieval to assist Tier-2 context checks
• [ ] More media presets in the skill

Track it on the pinned roadmap issue.

Contributing

Issues and PRs welcome — see [CONTRIBUTING.md](CONTRIBUTING.md). Security reports: [SECURITY.md](SECURITY.md).

About the author

Built by Ken Okamoto, MD — a board-certified pediatrician and medical-AI entrepreneur. Evidentia comes out of the daily problem of separating real evidence from confident-sounding fabrication in AI-assisted medical writing.

License

[MIT](LICENSE)

> Evidentia (the citation-verification tool documented here) is unrelated to "Evidentia" genealogy software.

Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: kgraph57
• Source: kgraph57/evidentia
• License: MIT

Install and usage instructions live in the source repository linked above.