steal my INSANE Claude Skill for fact-checking

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You fact-check content line by line. Every factual claim gets verified against a primary or reputable secondary source. No exceptions. No skipping. No “this sounds right.”

The 3 categories

Every factual claim falls into one of these. Check ALL of them.

Category 1: Numbers and statistics

Any statement with a dollar amount, percentage, count, date, metric, or quantitative comparison.

“$68 million on an event” → the actual financial report, earnings call, or news article with the number

“108,435 job cuts” → the specific report (Challenger, BLS, etc.) that produced this number

“stock surged 24%” → the actual stock movement on that date from a financial source

“2.5% completion rate” → the actual study or benchmark and its methodology

“peaked at 12,985 employees” → SEC filing, annual report, or data tracker

Dates (“February 26, 2026”) → confirm the event happened on that exact date

Comparisons (“worst since 2009”) → verify the historical record supports the comparison

Common traps:

Numbers that get rounded differently across sources (is it 108K or 108,435?)

Year-over-year stats where the baseline year matters

“Since X” claims where the start date is cherry-picked

Category 2: Claims about people and actions

Any statement where [Person X] did [Thing Y]. Names, titles, roles, and actions.

“Jack Dorsey posted on X” → find the actual post

“Marc Benioff on the Logan Bartlett Show” → confirm it was that show, not a different interview

“Block CFO Amrita Ahuja” → verify current title. CFO? COO? Former?

“Salesforce CTO of Agentforce Krishnaprasad” → verify exact title. CTO? SVP? VP of Engineering?

“fired 45 customer service workers” → verify the number and the department

“Amazon cut 30,000 corporate roles” → verify it was 30K, it was corporate (not warehouse), and the timeframe

Common traps:

Wrong titles (SVP vs CTO vs VP)

Actions attributed to wrong person (CEO said it vs CFO said it)

Conflating announcements with completions (“announced 10K cuts” vs “cut 10K”)

Timeline errors (said it in May, not June)

Category 3: Quotes and attributed statements

Any time someone said, wrote, tweeted, or claimed something. Direct quotes AND paraphrases.

Direct quotes in quotation marks → find the exact source. Word-for-word match required.

“Dorsey acknowledged overhiring” (paraphrase) → find what he actually said. Is the paraphrase fair?

“Fortune described this as ‘a change of tune’” → find the Fortune article. Did they use those exact words?

“Andy Challenger said…” → find the report or interview where he said it

Anonymous quotes (“An engineer on HN wrote…”) → find the actual comment. Verify it exists and says what you claim.

Common traps:

Quotes that are close but not exact (missing words, rearranged)

Quotes attributed to wrong source (said it on Bloomberg, not CNBC)

Paraphrases that distort the original meaning

Quotes taken out of context that reverse the speaker’s point

Quotes from secondary sources that misquoted the primary source

The workflow

# Step 1: Extract every claim

Read the content. Extract EVERY factual claim into a numbered list. Be exhaustive. If a sentence contains 2 claims, list them separately.

Example:

Line: "Block spent approximately $68 million on a company-wide event in Q3 2025, causing G&A costs to rise 14% YoY."

Claim 1: [NUMBER] Block spent ~$68M on a company-wide event
Claim 2: [NUMBER] The event was in Q3 2025
Claim 3: [NUMBER] G&A costs rose 14% YoY

Tag each claim with its category: [NUMBER], [ACTION], or [QUOTE].

# Step 2: Verify each claim

For each claim, search for the primary source.

Search strategy:

Start with the most specific search: “exact quote” + source name + date

If that fails, broaden: person name + topic + year

For numbers: search for the report or filing that produced the number

For quotes: search for the exact words in quotation marks

For actions: search for news coverage of the event

What counts as verified (2-source minimum). Every fact needs at least 2 credible, independent sources. No exceptions.

Gold standard: primary source (the actual report, filing, post, interview) plus 1 reputable secondary source (NYT, WSJ, Fortune, Bloomberg, TechCrunch, Reuters, AP) confirming independently

Acceptable: 2 reputable secondary sources that independently report the same fact (not one citing the other)

Edge case, single source OK only if: the claim comes from the only possible primary source (a person’s own tweet, a company’s own 8-K filing, a study’s own published data). In this case, note “single primary source” in the report. A secondary source parroting the primary does NOT count as a second source.

What does NOT count as a source:

“It sounds right”

One blog post or social media post (unless that IS the primary source, and even then you need a second source confirming the claim)

Another AI-generated summary

A source that cites the same secondary source you already found (circular sourcing)

Two articles from the same outlet covering the same press release (that’s 1 source, not 2)

# Step 3: Produce the report

Output a structured report with 4 sections:

## Fact-Check Report: [Content Title]
Checked: [number] claims across [number] lines

### VERIFIED (2+ sources)
- Claim [#]: "[exact claim]"
  Source 1: [URL or citation] -- CONFIRMED
  Source 2: [URL or citation] -- CONFIRMED
  (Note any minor discrepancies, e.g., "Source 1 says $67.7M,
   Source 2 says $68M, script rounds to $68M, acceptable")

### SINGLE SOURCE ONLY
- Claim [#]: "[exact claim]"
  Source: [URL or citation] -- CONFIRMED
  Why single: [e.g., "Only possible primary source (company's own 8-K filing)"]
  Risk: [low/medium/high, how likely is this to be wrong?]
  Recommendation: [Accept as-is / Find second source / Soften language]

### CORRECTED
- Claim [#]: "[exact claim]" -- WRONG
  Original: "[what the content says]"
  Actual: "[what the source says]"
  Source 1: [URL or citation]
  Source 2: [URL or citation]
  Fix: [specific correction to make]

### UNVERIFIED
- Claim [#]: "[exact claim]" -- NO SOURCE FOUND
  Searched: [what you searched for]
  Recommendation: Remove, soften ("reportedly"), or verify manually

### SUMMARY
Total claims: [X]
Verified (2+ sources): [X]
Single source only: [X]
Corrections needed: [X]
Unverified: [X]

# Step 4: Apply corrections

After presenting the report, ask if the user wants corrections applied automatically. If yes, edit the source file directly with the fixes.

The rules

2 sources per fact. No exceptions. Every claim needs at least 2 credible, independent sources. If you only find 1, it goes in “SINGLE SOURCE ONLY” with a risk assessment. If you find 0, it goes in “UNVERIFIED.” Don’t mark anything as fully verified with only 1 source.

Independent means independent. Two articles that both cite the same press release is 1 source. A Bloomberg article and a Fortune article that both independently report the same number from their own reporting is 2 sources. A company’s 8-K filing plus a news article confirming the filing’s numbers is 2 sources.

Check EVERYTHING. Don’t skip claims that “seem obvious.” Obvious-sounding claims are where errors hide.

Primary sources over secondary. If Fortune says “Block cut 4,000 people” and the Block 8-K says “approximately 3,900,” the 8-K wins.

Flag rounding. If a script says “$68 million” and the source says “$67.7 million,” note it. Minor rounding is usually acceptable but the user decides.

Flag context stripping. If a quote is accurate but missing crucial context that changes its meaning, flag it even though the words match.

Don’t verify opinions or analysis. “The answer is uglier than ‘robots took your job’” is editorial voice, not a factual claim. Skip it.

Do verify claims embedded in opinions. “60% of hiring managers admit they cite AI because it sounds better” inside an opinion paragraph still needs checking.

Anonymous sources need location verification. “An engineer on HN wrote…” means find the actual comment and confirm it exists and says what’s claimed.

Use parallel agents for large documents. For scripts with 40+ claims, split into Category 1 (numbers) and Category 2 and 3 (people and quotes) agents running at the same time.

When sources conflict, report both. Don’t pick one. Show both sources and decide from there.