Adversarial citation and claim audit for any document — "do these sources actually say what the text claims?" Takes a markdown file, URL, or pasted draft (including this repo's own pulse/verdict briefs), extracts every checkable claim, then fans out verifier sub-agents instructed to refute, not confirm: does the cited link resolve AND assert the claim as stated, is the source primary or a laundered secondary write-up, has the claim gone stale. Emits a graded audit table — VERIFIED / MISATTRIB...
Scanned 8/31/2026
Install to Claude Code
npx -y skills add duthaho/skillhub --skill factcheck --agent claude-codeInstalls into .claude/skills of the current project.
Are you the author of Factcheck?
Add the live security badge to your README — it updates automatically with every re-scan.
[](https://www.skillsdirectory.com/skills/duthaho-factcheck)More formats (shields.io, HTML) on the badges page.
---
name: factcheck
description: >-
Adversarial citation and claim audit for any document — "do these sources
actually say what the text claims?" Takes a markdown file, URL, or pasted
draft (including this repo's own pulse/verdict briefs), extracts every
checkable claim, then fans out verifier sub-agents instructed to refute,
not confirm: does the cited link resolve AND assert the claim as stated,
is the source primary or a laundered secondary write-up, has the claim
gone stale. Emits a graded audit table — VERIFIED / MISATTRIBUTED /
UNSUPPORTED / STALE / UNCHECKABLE — with a quoted passage as evidence for
every grade, saved to out/factcheck/. Advisory: it grades, the human
edits. Use when the user wants to check citations, verify sources, or
audit a report, post, or brief — e.g. "/factcheck <doc>", "verify the
sources in this", "are these citations real?", "is this actually true?".
For researching a fresh topic use pulse; for judging code changes use
done.
---
# factcheck — do the sources say that?
`/factcheck <path | URL>` — audit a document's claims against its sources
`/factcheck <path> focus <section/topic>` — audit only part of a long document
Answer one question: **for each claim this document makes, is there a source
that actually asserts it?** The documented failure mode of cited writing —
human and agent alike — is not missing links; it's links that resolve to
pages that *don't say that*. A working URL is the weakest form of evidence
there is. This audit replaces "it has citations" with "here is the passage."
## Step 0 — Scope the audit
Read the document (WebFetch if a URL; ask for a paste if it's paywalled).
Then size the job and say which tier you picked:
- **Small** (≤ ~10 checkable claims): verify inline, no sub-agents — the
fan-out below would cost more than it saves.
- **Standard**: fan out, batching ~5–8 claims per verifier.
- **Focused**: the user named a section or topic → extract only there, note
in the audit header that the rest was not examined.
If the document has **no citations at all**, say so up front — the audit's
question shifts from "does the cited source say this" to "does support for
this exist anywhere", and UNSUPPORTED becomes the default grade to beat.
## Step 1 — Extract the checkable claims
Walk the document and number every **checkable claim**: factual, specific,
and in principle verifiable — statistics, quotes, "X said/announced Y",
version numbers, benchmark results, historical facts, "studies show".
For each claim record: a short restatement, its **locator** (section
heading or line), the **cited source** if any, and whether it's
**date-sensitive** (anything with "currently", "latest", a version, or a
number that drifts).
Skip pure opinion and analysis — but flag **opinion dressed as fact**
("it is widely known that...") as a finding in its own right, ungraded.
## Step 2 — Adversarial verification (fan out)
Spawn verifier sub-agents (`subagent_type: "Explore"`), each with a batch
of claims and the same standing instruction: **try to refute each claim,
not confirm it** — a verifier hunting for agreement finds it whether it
exists or not. Per claim:
1. **Fetch the cited source.** Find the exact passage that supports or
contradicts the claim — and **quote it verbatim**. No passage, no
verification, regardless of how relevant the page looks.
2. **Trace laundered sources.** If the citation is a secondary write-up (a
blog post about a paper, a news story about an announcement), follow it
to the source that *owns* the claim — the paper, the changelog, the
transcript. Grade against the owner; note the laundering.
3. **Check the date.** For date-sensitive claims, one search pass for
newer, superseding evidence — a claim can be faithfully cited and still
be wrong today.
4. **Uncited claims:** one honest search for a supporting primary source.
Found → grade normally and record the found source. Not found →
UNSUPPORTED, with the search noted.
**Grades** (exactly one per claim):
| Grade | Meaning |
|---|---|
| **VERIFIED** | The source asserts the claim as stated — passage quoted. |
| **MISATTRIBUTED** | The source is real but says something materially different — both versions quoted. |
| **UNSUPPORTED** | Link dead, source nonexistent, or no source found that asserts it. |
| **STALE** | Was true when written; superseded — the newer evidence quoted and dated. |
| **UNCHECKABLE** | Paywalled, offline, or genuinely unverifiable — stated, never guessed around. |
**Lossless hand-off:** each verifier writes full findings (quotes, URLs,
search trails) to `out/factcheck/.work/<batch>.md` and returns a compact
summary; build the audit from the files, not the summaries — a quote
flattened by a relay is no longer evidence.
## Step 3 — The audit
Render in chat, then save. Findings first, worst first:
```markdown
# Factcheck: <document title> — <YYYY-MM-DD>
**Document:** <path/URL> · **Claims examined:** N (of M total; scope note if focused)
**Score:** X VERIFIED · X MISATTRIBUTED · X UNSUPPORTED · X STALE · X UNCHECKABLE
## Findings that matter most
1–3 sentences: the riskiest problems (misattributions and unsupported
central claims outrank stale trivia), any laundering pattern, any cluster.
## Claim-by-claim
| # | Claim | Locator | Cited source | Grade | Evidence |
|---|---|---|---|---|---|
(evidence column = the quoted passage or the reason, always)
## Laundered sources
citation → owning source, per case (omit section if none)
## Date-sensitive claims
what to re-check and when (omit if none)
```
Save to `out/factcheck/<slug>-<YYYY-MM-DD>.md` (`<slug>` from the document
title; date via `date +%F` — never guessed). Create the folder if needed;
committing the audit is the user's call. Then **offer** — never do unasked —
the follow-ups:
annotate the original with inline flags, or draft corrected text for the
failing claims.
## Guardrails
- **A resolving link proves nothing.** Verification is a quoted passage or
it didn't happen.
- **Refute-first.** Every verifier hunts for the disconfirming reading;
when a grade is genuinely arguable, take the lower one and say why.
- **Primary sources own claims.** A write-up of a paper is not the paper;
grade against the owner.
- **Unknowns stay UNCHECKABLE.** Never guessed, averaged, or rounded up to
VERIFIED — an honest "couldn't check" is a finding, not a failure.
- **Advisory, not editorial.** The audit grades; the human decides what to
do about it. Never edit the audited document without being asked.
- **This repo's outputs are fair game.** Auditing a pulse or verdict brief
with fresh-context verifiers is the intended use, not an insult — the
writer of a claim is the worst-placed agent to check it.
Is this your skill, or is something wrong with this listing? Request removal or report an issue. Author removals are honored within 72 hours.
No comments yet. Be the first to comment!