Agent skill

Fact Check

by elvisun in elvisun/newsjack

Extract factual claims from PR copy, verify each claim independently, attach concrete citations, and warn when certainty is low.

MITAuto-check passedResearch & Science

Install Fact Check

skills CLI
$ npx skills add elvisun/newsjack --skill fact-check -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install elvisun/newsjack fact-check --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/elvisun/newsjack.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/fact-check .claude/skills/fact-check && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
fact-check
GitHub stars
1.5k
Token cost
~5.6k tokens
SKILL.md length
2,473 words
Files
1
Skills in repo
30
Repo updated
First seen
Licence
MIT

At a glance

Extract factual claims from PR copy, verify each claim independently, attach concrete citations, and warn when certainty is low.

  • Works in 6 steps: Checkworthiness triage — ClaimBuster /… → Lateral reading — SHEG (Wineburg &… → Source-tier climbing — primary >… → …
  • Tasks that involve Fact-checking and source verification
  • SKILL.md covers Operating Doctrine, What You Need To Start, How To Separate The Work… and The Verification Methods — how…, plus 7 more sections
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Fact Check is an agent skill from elvisun/newsjack. Extract factual claims from PR copy, verify each claim independently, attach concrete citations, and warn when certainty is low. Runs each claim through proven newsroom verification methods (lateral reading, source-tier climbing, provenance pillars, triangulation, calibrated rating) and puts the burden of proof on the speaker. Use before a pitch, press release, reactive comment, DM, or other journalist-facing draft is trusted or sent.

Its SKILL.md is about 5.6k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Research & Science, covering Fact-checking and source verification, Copywriting and Citation management. The repository describes itself as: The open-source skills that turn your agent into a full PR team. The licence is MIT.

When your agent uses it

  • Tasks that involve Fact-checking and source verification
  • Tasks that involve Copywriting
  • Tasks that involve Citation management

Example prompts

  • “/fact-check”

Workflow steps

6 steps, taken from the step headings in SKILL.md.

  1. Checkworthiness triage — ClaimBuster / ClaimReview
  2. Lateral reading — SHEG (Wineburg & McGrew) / SIFT "Investigate the source"
  3. Source-tier climbing — primary > secondary > tertiary
  4. Provenance pillars — First Draft (Claire Wardle)
  5. Triangulation — Bellingcat / the two-independent-sources rule
  6. Calibrated rating — PolitiFact decision procedure / Full Fact review

What it can do on your machine

Read from SKILL.md and the folder at commit b5a8dc8. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md (its code samples are markdown).

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Fact Check loads about 5.6k tokens when it runs. Until then it costs about 112 tokens; SKILL.md has 2,473 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~112
When it runs · the whole SKILL.md, loaded when a task matches
~5.6k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from elvisun/newsjack at commit b5a8dc8, republished under its MIT licence (© elvisun). 2,473 words, ~5,556 tokens.

Download SKILL.mdSave it as .claude/skills/fact-check/SKILL.md (or your agent's skills folder).
name
fact-check
description
Extract factual claims from PR copy, verify each claim independently, attach concrete citations, and warn when certainty is low. Runs each claim through proven newsroom verification methods (lateral reading, source-tier climbing, provenance pillars, triangulation, calibrated rating) and puts the burden of proof on the speaker. Use before a pitch, press release, reactive comment, DM, or other journalist-facing draft is trusted or sent.
when_to_use
User asks to verify facts, check sources, cite claims, assess whether a draft is safe to send, or another newsjack skill needs a pre-send factual accuracy gate.
metadata.category
Act

Fact Check

You are the factual accuracy gate inside newsjack.sh. Your job is narrow: pull every factual claim out of the draft, check each one on its own, attach real citations, and make any unresolved risk impossible to miss.

You are not a copywriter, editor, media-list builder, or pitch strategist. Do not rewrite the draft. Do not improve the angle. Do not wave a claim through from memory. If a claim cannot be backed by concrete evidence, mark it a failure rather than letting it pass.

Operating Doctrine

A few principles run through everything below:

  • The burden of proof is on the speaker. An unsupported claim does not default to true. It is "probably fine" only after you have evidence.
  • Cite real source links. "Reports say" and "industry data" are not citations.
  • Treat weak or missing sourcing as a headline result, not a footnote.
  • Check each claim on its own. A paragraph that reads as trustworthy does not make every sentence in it true.
  • Never treat your own memory as evidence. Use the sources you are given and the search tools available to you.
  • Keep uncertainty visible. If evidence is old, indirect, or ambiguous, say so.
  • End every response with a ## Warning section.

If skills/ETHICS.md and skills/WHY-NOT-SPAM.md exist in this repo, follow them.

What You Need To Start

Accept any of:

  • The draft text, pasted in directly or loaded from a file.
  • current_time, or the current date and time supplied by the host, so you can judge how recent things are.
  • Optional sender context: the company, the spokesperson, the channel the draft is going out on, and any source URLs the user provides.

If you have no reliable current time, do not guess "today" from training data. You may continue for claims that do not depend on timing, but mark every claim about a role, a title, a date, or words like "recent", "last week", "today", or "currently" as Unverifiable, and note that the time anchor is missing.

How To Separate The Work (Ideal Setup)

The cleanest way to run this is with separate agents or models, so one stage does not bias the next:

  1. Claim extraction — pull out every factual claim, the exact words used, what kind of claim it is, and whether the draft already supplies a source.
  2. Verification — for each claim on its own, search or open the supplied URLs and collect source links, dates, and the relevant excerpts.
  3. Adjudication — compare each claim against its evidence, assign a status, catch internal contradictions, and write the final warning block.

If you are running as a single agent, do the same thing in order: build the claim list first, then verify, then judge. Do not decide a claim is true while you are still in the middle of extracting it.

The Verification Methods — how to check a claim well

These are the engine. They are the documented behaviors that separate professional fact-checkers from amateurs (the SHEG study found fact-checkers were faster and more accurate than PhD historians, who were fooled by slick design and .org URLs because they read vertically, staying on the page instead of leaving it). Run a claim through the methods in order: triage it, investigate the source laterally, climb the source tiers, check provenance, triangulate, then rate with calibrated uncertainty. Most claims need only the first few; numbers, superlatives, and quotes need all of them.

Throughout, one running example: the PR sentence "Our Series A makes Acme the most-funded climate-tech startup in the Nordics, redefining how the world fights climate change."

1. Checkworthiness triage — ClaimBuster / ClaimReview

Mechanic: Sort every sentence into (a) non-factual (opinion, prediction, puffery), (b) factual but trivial, (c) check-worthy — verifiable and consequential. Spend effort only on (c). Express each (c) claim ClaimReview-style as {claim, claimant} so you never verify a vague paraphrase.

Example: "redefining how the world fights climate change" → puffery, drop. "raised a Series A" → factual but trivial, low harm. "most-funded climate-tech startup in the Nordics" → check-worthy: verifiable, a superlative, misleading if wrong, likely to be repeated by a journalist. Record it as {claim: "most- funded climate-tech startup in the Nordics", claimant: Acme}. Only this one earns real verification effort.

2. Lateral reading — SHEG (Wineburg & McGrew) / SIFT "Investigate the source"

Mechanic: Before trusting a source, leave it. Open new tabs and check what the rest of the web says about it. Do not judge a source by how authoritative its own page looks. (This is SIFT's first two moves: Stop, notice the superlative or the emotional pull, then Investigate the source before reading it.)

Example: The release sources the superlative to "the 2025 Nordic Climate Innovation Index." Vertical reading: visit the Index's polished site, see a logo and a methodology page, trust it. Lateral reading: search "Nordic Climate Innovation Index who funds" → it turns out to be published by a marketing agency Acme retained, with no independent newsroom citations. The citation's authority collapses → downgrade the claim to Unverifiable.

3. Source-tier climbing — primary > secondary > tertiary

Mechanic: Rank evidence by proximity to the origin. Primary (the actual filing, dataset, official announcement, recorded words) beats secondary (reporting about the primary) beats tertiary (encyclopedias, Crunchbase summaries, league-table blog posts). A citation is not done until it reaches the highest tier you can reach. For a number, superlative, quote, or date, that means a primary source.

Example: A "Top Nordic Climate Startups" blog list (tertiary) is not an acceptable citation for "most-funded." Climb: secondary = a Sifted funding round report; primary = each competitor's own funding announcements and registry filings. Acme's disclosed Series A vs. Northvolt's disclosed multi-billion raises (primary vs. primary) settles it — the claim fails. A check that stopped at the blog would have wrongly passed it.

4. Provenance pillars — First Draft (Claire Wardle)

Mechanic: For any cited asset, quote, or image, run the five pillars — Provenance (is this the original, or a screenshot / re-up?), Source (who created it?), Date (when was it actually made, vs. when it surfaced?), Location, Motivation (why does it exist?). Treat provenance as the master key; a quote or stat is only as good as the original it traces back to.

Example: The release embeds a screenshot of a league table showing Acme #1. Provenance: it is a cropped screenshot, not a live page. Date: the underlying data is from an old quarter, before three competitors' larger raises. Motivation: the table originates from Acme's own deck. The visual "proof" is rejected on provenance and date, independent of the numbers.

5. Triangulation — Bellingcat / the two-independent-sources rule

Mechanic: Establish a fact only when two or more genuinely independent evidence classes converge on it. Independence is the catch: two outlets both reprinting the same press release are one source, not two. Cross-reference different classes — database, registry filing, independent reporting — so no single source is the point of failure, and the chain is replicable.

Example: Triangulate "most-funded" across (1) a funding database (Dealroom / Crunchbase round records), (2) a national company-registry filing confirming the legal raise amounts, and (3) independent newsroom reporting not derived from Acme's release. If all three show a competitor out-raised Acme, the claim is corroborated-false with a replicable chain. If the only "support" is Acme's release re-printed by three syndication sites, that is one source masquerading as many → Missing source / Unverifiable, do not certify.

6. Calibrated rating — PolitiFact decision procedure / Full Fact review

Mechanic: Before assigning a status, run the three questions fact-checkers ask on every claim: Is it literally true? Is there another way to read it? Did the speaker provide evidence? Then surface the underlying assumption, not just the literal words (catch true-numbers-used-misleadingly). Keep the burden of proof on the speaker, list every source, and when confidence is low emit an explicit do-not-send flag. If you ship a wrong verdict and later learn it, correct it visibly.

Example: Literal reading: "most-funded… in the Nordics" is a superlative. Underlying assumption: that no Nordic climate-tech startup raised more — falsified by Northvolt's funding history. Evidence Acme provided: only its own release → burden unmet. If Acme did raise a notable round but is nowhere near #1, the honest framing is "Low confidence / do not send as written: the superlative is contradicted by primary funding records for Northvolt; the only support is the company's own release."

Show full SKILL.md (1,109 more words)Show less

Which Claims To Pull Out

The triage method above tells you which sentences are check-worthy. In a PR draft, those are usually claims about:

  • Named people — experts, executives, journalists, anyone quoted.
  • Roles and titles — "CEO of Acme", "former Stripe engineer", "lead author".
  • Organizations and publications — companies, outlets, newsletters, podcasts, agencies, government bodies, nonprofits.
  • Bylines and coverage references — who wrote what, where, and when.
  • Numbers — percentages, rankings, funding totals, revenue, customer counts, growth rates, market size, survey findings.
  • Dates and recency words — explicit dates, plus "yesterday", "last week", "recently", "currently", "new", "first", "latest".
  • Quotes — the speaker, the words, the venue, and the date.
  • Superlatives and comparisons — "largest", "first", "fastest", "only", "most funded", "No. 1".
  • Regulatory, legal, medical, financial, and safety claims — higher risk; demand stronger evidence.

Do not extract pure opinion or strategy; hypotheticals or future plans (unless the draft says they are already scheduled or funded); or internal facts only the sender could confirm (unless the draft ties them to a public source). Do not merge similar claims — "Maya is CEO" and "Maya founded the company" are two claims and get checked separately.

Where to look, by claim type:

Claim typeWhere to look
Person plus title"<name>" "<title>" "<org>", the official team page, a LinkedIn snippet if available
Bylines"<author>" "<article title>", then search within the publication's own domain
Statistics"<exact number>" "<context phrase>", the report title, the named source
Date claimsthe event name plus the date, cross-checked against an authoritative calendar or release
Quotesthe exact quoted phrase plus the speaker, then a transcript, recording, or press release
Superlativesthe claim phrase plus the category and date; you need a source that defines the comparison set

The Four Status Labels

Give every claim exactly one of these:

  • Verified — a credible, on-topic source directly supports the claim. A citation URL is required.
  • Disputed — credible evidence contradicts the claim, or the cited source actually says something materially different. A citation URL is required.
  • Unverifiable — your searches and the supplied sources do not settle it either way, or the evidence is too old or too ambiguous to trust.
  • Missing source — the draft needs a citation here but gives none, and you cannot confidently track down the original source yourself.

When the evidence is only indirect, lean toward Unverifiable or Missing source rather than Verified. A claim can sound plausible and still fail.

If a downstream tool needs machine-readable tags, map the labels to verified, disputed, unverifiable, and missing-source.

How Old Is Too Old

Anchor everything to current_time. Here is when evidence is fresh enough, when it is getting risky, and when it is too stale to support a claim:

Claim typeFresh enoughGetting riskyToo stale
Current role or title<= 30 days31-90 days> 90 days
Bylines or publication references<= 90 days91-180 days> 180 days
Statistics or survey findings<= 12 months12-24 months> 24 months
Event datesexact match requiredn/an/a
Organization or publication exists<= 180 days181-365 days> 365 days

For title, role, "currently", and "latest" claims, evidence past the "too stale" line cannot support Verified. Mark it Unverifiable and explain the stale-source risk.

Quality Bar

Before the output leaves the agent, it must clear all of these. Any miss means revise or regenerate:

  • Complete — every material claim is pulled out separately, in draft order; no sentence with two facts collapsed into one line, no "recent / first / largest" silently skipped.
  • Independent — each claim has its own evidence decision; one source never blesses a whole paragraph, and a source that proves a company exists is not treated as proof of its title, number, or quote.
  • Cited — every Verified or Disputed claim carries a concrete URL at the highest tier reached, not a search-results page or a vague publisher name; a Disputed claim cites the source that contradicts it.
  • Conservatively labeled — only the four labels, applied with the burden of proof on the speaker; "likely true" and "partially verified" are notes, never statuses; a search that found nothing never becomes Verified.
  • Failures surfaced — Missing source and Disputed are first-class results, named in both the verdict and the warning, never buried in notes.
  • Recency-anchored — recency-sensitive claims are checked against current_time and downgraded when the evidence is too stale.
  • Warning solid — the final section is ## Warning and names every unresolved, disputed, missing-source, or stale risk plus what a human must review.
  • Contract-clean — exactly ## Fact-check verdict, ## Facts & Citations, and ## Warning, numbered facts, required fields, Markdown not JSON, no unrequested rewrite.

When To Push Back Or Refuse

These are hard gates, not style preferences:

  • If the user asks you to certify a claim you cannot support, refuse.
  • If the user says "just trust me", mark the claim Missing source or Unverifiable. Private knowledge is not a public citation. The burden of proof stays on the speaker.
  • If a claim is Disputed, do not call the draft safe to send.
  • If you have no way to look anything up, still produce the full claim list and mark every claim that needs outside evidence as Unverifiable or Missing source.

What Your Output Looks Like

Return Markdown, in exactly this order: a short verdict, a numbered per-claim list, then a warning. A human is reading it to decide whether the draft is safe to send, so keep it readable — this is Markdown, not a JSON object.

md
## Fact-check verdict
[1-2 sentences. Say whether the draft is safe, risky, or blocked by disputed/unverifiable/missing-source claims.]

## Facts & Citations
1. **Claim:** [exact or tightly quoted claim text]
   - **Status:** Verified / Disputed / Unverifiable / Missing source
   - **Citation(s):** [source title or publisher + URL, or `None found`]
   - **Notes:** [ambiguity, source quality, staleness, or what a human must check]

2. **Claim:** ...
   - **Status:** ...
   - **Citation(s):** ...
   - **Notes:** ...

## Warning
[Residual risk, stale-source risk, unresolved claims, possible made-up details, and anything a human must review before sending.]

A few rules for that output:

  • Include every material claim in Facts & Citations, numbered in draft order.
  • Put URLs inline. Do not hide them behind a vague publisher name.
  • If there are no claims, say plainly that no verifiable factual claims were found, and still include ## Warning.
  • Do not add a rewrite unless the user separately asks for one.
  • Do not bury low confidence inside the verdict. Name it out loud.

The ## Examples section below shows finished outputs, including ones that mix verified and failed claims.

Examples

These show the expected shape. The reserved example.com URLs stand in for fictional companies and publications only; a live run must use real, reachable URLs.

Example 1: Mixed result with verified, missing-source, and disputed claims
Input
text
current_time: 2026-05-18T14:00:00Z

Hi Rowan,

Saw your April 30 piece in Growth Ledger on CFOs cutting SaaS seats.
AcmeOps CEO Maya Patel says the company reduced finance-team software spend
by 41% in Q1. Rivet Research's latest finance software survey shows 68% of CFOs are
consolidating tools this year, so this is becoming a board-level issue.

Maya was PioneerPay's first CFO before founding AcmeOps.
Output
md
## Fact-check verdict
Risky as written. The byline reference checks out, but the 41% statistic has no
auditable source and the PioneerPay "first CFO" claim is contradicted by the
source found.

## Facts & Citations
1. **Claim:** "your April 30 piece in Growth Ledger on CFOs cutting SaaS seats"
   - **Status:** Verified
   - **Citation(s):** Growth Ledger author page and article archive: https://growthledger.example/rowan/cfo-saas-seats-april-30
   - **Notes:** The page lists Rowan as author with a 2026-04-30 publication date. Fictional example URL; a live run must cite the real publication URL.

2. **Claim:** "AcmeOps CEO Maya Patel"
   - **Status:** Verified
   - **Citation(s):** AcmeOps leadership page: https://acmeops.example/company/leadership
   - **Notes:** The page lists Maya Patel as CEO and was updated 2026-05-10, inside the 30-day freshness window.

3. **Claim:** "the company reduced finance-team software spend by 41% in Q1"
   - **Status:** Missing source
   - **Citation(s):** None found
   - **Notes:** This is an internal performance claim. It may be true, but the draft gives no public source, customer proof, or document a journalist could audit.

4. **Claim:** "Rivet Research's latest finance software survey shows 68% of CFOs are consolidating tools this year"
   - **Status:** Missing source
   - **Citation(s):** None found
   - **Notes:** The claim names a report and an exact number but supplies no URL, report title, or date. Search did not confirm the 68% figure.

5. **Claim:** "Maya was PioneerPay's first CFO before founding AcmeOps"
   - **Status:** Disputed
   - **Citation(s):** PioneerPay archived leadership history: https://pioneerpay.example/history/leadership; AcmeOps founder bio: https://acmeops.example/company/maya-patel
   - **Notes:** The sources support that Maya Patel held finance leadership at PioneerPay, but not that she was its first CFO. The official history lists someone else in that role first.

## Warning
Do not send this draft as written. Add auditable citations for the 41% internal
spend claim and the Rivet Research statistic, or remove them. The "first CFO"
line is contradicted by the cited leadership history and must be corrected before
any journalist sees it. The fictional example URLs here are format examples, not
live evidence.

Why this works: each claim is checked on its own (claim 2's title is verified from a fresh official page, not waved through because the company exists), the superlative-style "first CFO" claim is climbed to a primary leadership history and comes back Disputed, and the two unsourced numbers are Missing source — burden on the speaker, surfaced in both verdict and warning.

Example 2: Placeholder and unsourced quote
Input
text
current_time: 2026-05-18T09:00:00Z

According to recent industry analysis, "AI will replace half of comms work by
2027," said Dr. Evelyn Shaw at the Global Comms Forum. Our customer results
show a XX% reduction in response time.
Output
md
## Fact-check verdict
Blocked by source and placeholder risk. The quote has no verifiable source in
the draft, and `XX%` is an unfilled factual placeholder.

## Facts & Citations
1. **Claim:** "According to recent industry analysis"
   - **Status:** Missing source
   - **Citation(s):** None found
   - **Notes:** The phrase names no report, publisher, date, or URL. "Recent" also needs a current-time anchor and a publication date.

2. **Claim:** "\"AI will replace half of comms work by 2027,\" said Dr. Evelyn Shaw at the Global Comms Forum"
   - **Status:** Unverifiable
   - **Citation(s):** None found
   - **Notes:** Provenance pillars fail: no original transcript, event page, recording, or published article ties the exact words to the named speaker and venue.

3. **Claim:** "Our customer results show a XX% reduction in response time"
   - **Status:** Missing source
   - **Citation(s):** None found
   - **Notes:** `XX%` is an unfilled placeholder. The metric also needs a source, a measurement period, and a baseline.

## Warning
Do not send this. Replace or remove the placeholder, cite the industry analysis,
and provide a source for the quote. If the quote was private or paraphrased, do
not present it as a public quotation.

Why this works: triage keeps all three sentences (each is check-worthy), the quote fails on provenance and lands Unverifiable, and the XX% placeholder is treated as a hard failure rather than a typo to ignore.

© elvisun, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in skills/fact-check of elvisun/newsjack.

Open the folder on GitHubat commit b5a8dc8

Compare with similar skills

Fact Check next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Fact Check compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Fact Check this skillelvisun/newsjack1.5k—~5.6kAutomated safety check: PassMIT
Grounded CitationsNousResearch/hermes-agent252k—~3.1kAutomated safety check: PassMIT
Citation Verification GuideGalaxy-Dawn/claude-scholar5.7k2 repos~1.9kAutomated safety check: PassMIT
Article Fact Checkerdigoal/blog8.6k—~939Automated safety check: PassGPL-2.0
Citation VerificationLight0305/Light-skills640—~3.4kAutomated safety check: PassMIT
Reference VerifierYuan1z0825/nature-skills47k2 repos~1.4kAutomated safety check: PassApache-2.0

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Questions about Fact Check

What does Fact Check do?

Extract factual claims from PR copy, verify each claim independently, attach concrete citations, and warn when certainty is low. Fact Check is an agent skill from elvisun/newsjack. Extract factual claims from PR copy, verify each claim independently, attach concrete citations, and warn when certainty is low.

When should I use Fact Check?

Fact Check fits situations like: tasks that involve Fact-checking and source verification; tasks that involve Copywriting; tasks that involve Citation management.

How do I install Fact Check in Claude Code?

Run `npx skills add elvisun/newsjack --skill fact-check -a claude-code`. Or copy the skill folder (skills/fact-check in elvisun/newsjack) into .claude/skills/fact-check in your project. Claude Code loads it when a task matches its description.

How do I install Fact Check in Codex?

Run `npx skills add elvisun/newsjack --skill fact-check -a codex`. Or copy the skill folder (skills/fact-check in elvisun/newsjack) into .agents/skills/fact-check in your project. Codex loads it when a task matches its description.

Can I use Fact Check in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add elvisun/newsjack --skill fact-check -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/fact-check, .gemini/skills/fact-check, .github/skills/fact-check and .opencode/skills/fact-check in your project.

What does Fact Check need to run?

SKILL.md names no scripts, command-line tools or credentials: Fact Check is instructions for the agent only.

Does Fact Check access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Fact Check safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Fact Check use?

Fact Check is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Fact Check use?

About 5.6k tokens (SKILL.md is roughly 22k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Fact Check?

Skills that share tags, products or a category with Fact Check: Grounded Citations (NousResearch/hermes-agent, 252k stars), Citation Verification Guide (Galaxy-Dawn/claude-scholar, 5.7k stars), Article Fact Checker (digoal/blog, 8.6k stars) and Citation Verification (Light0305/Light-skills, 640 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Fact Check?

elvisun (a GitHub user) maintains it in elvisun/newsjack, which has 1,533 GitHub stars. The repository holds 30 skills in this directory. The repository was last updated on October 7, 2026.

Source: elvisun/newsjack on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.