| name | blog-factcheck |
| description | Verify statistics and claims in blog posts by fetching cited source URLs and checking if the claimed data actually appears on the page. Extracts all statistical claims (numbers, percentages, named sources), fetches each cited URL via WebFetch, and scores match confidence (exact match 1.0, paraphrase 0.7-0.9, not found 0.0). Flags uncited claims as UNVERIFIED. Use when user says "fact check", "verify statistics", "check sources", "validate claims", "factcheck", "source verification".
|
| user-invokable | true |
| argument-hint | [file] |
| license | MIT |
| id | blog-factcheck |
| domain | content |
| invoked_by | ["blog-reviewer","blog-writer"] |
| depends_on | [] |
Blog Fact-Check
Verify statistics, claims, and source attributions in blog posts. Pure Antigravity
pipeline with no external NLP dependencies.
Workflow
Step 1: Read the Blog Post
Read the target file and identify all sections containing data claims.
Step 2: Extract Statistical Claims
Scan the full text for every claim that includes a number, percentage, dollar
amount, or named source. Build a claims list with these fields:
| Field | Description |
|---|
| claim_text | The exact sentence or phrase containing the statistic |
| value | The numeric value (e.g., "42%", "$1.2M", "3x") |
| attribution | Named source if present (e.g., "HubSpot", "Gartner 2025") |
| url | Cited URL if present (from markdown link or parenthetical) |
| location | Heading or line number where the claim appears |
Step 3: Verify Cited Claims
For each claim that includes a URL:
- Fetch the source page via WebFetch
- Search the returned content for the specific numeric value
- If exact value found, check surrounding context matches the claim topic
- Assign a confidence score (see Verification Scoring below)
Process claims sequentially to avoid rate-limiting source sites.
Step 4: Flag Uncited Claims
For claims without a URL:
- Mark status as UNVERIFIED
- Suggest a search query the user can run to find a source
- If the attribution names a specific organization, suggest their domain
Step 5: Generate Verification Report
Output the full results table, summary statistics, and recommended actions.
Claim Extraction Patterns
Identify claims matching these structures:
Fully cited (highest priority):
[Number]% [claim] ([Source], [Year]) - parenthetical citation[claim] [Number]% ... [markdown link to source] - inline linkAccording to [Source], [Number]... - attribution lead
Uncited statistics (flag for sourcing):
[Number]% of [noun phrase] - standalone percentage[Number]x more/less/higher/lower - multiplier claims
