--- frontmattername: Fact Check
description: This skill should be used when the user asks to "verify claims", "fact check", "validate documentation", "check sources", or needs verification of external source references. Provides patterns for systematic fact verification using Context7 and WebSearch.
version: 0.2.0
<error_escalation inherits="core-patterns#error_escalation">
<examples>
<example severity="low">Claim cannot be verified due to missing documentation</example>
<example severity="medium">Conflicting information from different sources</example>
<example severity="high">Claim directly contradicts authoritative source</example>
<example severity="critical">Security-related claim is incorrect</example>
</examples>
</error_escalation>
<patterns>
<pattern name="claim_extraction">
<description>Identify claims that reference external sources for verification</description>
<decision_tree name="when_to_use">
<question>Does the content reference external documentation or standards?</question>
<if_yes>Apply claim extraction to identify verifiable assertions</if_yes>
<if_no>No fact-checking needed for this content</if_no>
</decision_tree>
<example>
Claim types to extract:
Library API claims: "useState returns a tuple"
Documentation references: "according to the React docs"
Standard compliance: "follows WCAG 2.1 AA"
Version-specific behavior: "in React 18, Suspense..."
Performance claims: "O(log n) complexity per MDN"
Version-specific example:
Claim: "React 18 introduces automatic batching for all updates"
Verification: Query Context7 with topic="batching" for React 18 docs
Result: Confirmed - React 18 automatically batches state updates inside promises, setTimeout, and native event handlers
</example>
Threshold: Flag claims with confidence below 80
</example>
Web standards: WebSearch with domain filters
MDN Web Docs: developer.mozilla.org
W3C: w3.org
WHATWG: html.spec.whatwg.org
OWASP: owasp.org
</example>
<best_practices>
<practice priority="critical">Use Context7 as primary source for library documentation claims</practice>
<practice priority="critical">Flag all claims with verification confidence below 80</practice>
<practice priority="critical">Document evidence source for each verification</practice>
<practice priority="high">Prefer libraries with Context7 trust score 7+ for verification</practice>
<practice priority="high">Use WebSearch fallback when Context7 unavailable</practice>
<practice priority="medium">Include direct quotes from sources as evidence</practice>
<practice priority="medium">Note when verification source has version mismatch</practice>
</best_practices>
<anti_patterns>
<avoid name="assumption_verification">
<description>Marking claims as verified without actual source check</description>
<instead>Always query Context7 or WebSearch for evidence before marking verified</instead>
</avoid>
<avoid name="single_source_reliance">
<description>Relying on only one source for disputed claims</description>
<instead>Cross-reference with multiple sources when confidence is borderline (70-85)</instead>
</avoid>
<avoid name="ignoring_version_context">
<description>Verifying claims without considering version differences</description>
<instead>Note version context and verify against appropriate documentation version</instead>
</avoid>
<avoid name="over_verification">
<description>Attempting to verify every statement including obvious facts</description>
<instead>Focus on claims referencing external sources, APIs, and specifications</instead>
</avoid>
</anti_patterns>
<rules priority="critical">
<rule>Always verify claims against authoritative sources before flagging</rule>
<rule>Use Context7 as primary source for library and framework claims</rule>
<rule>Flag claims with confidence below 80 in fact check results</rule>
<rule>Document evidence source for every verification</rule>
</rules>
<rules priority="standard">
<rule>Use WebSearch as fallback when Context7 unavailable</rule>
<rule>Prefer official documentation over third-party sources</rule>
<rule>Note version context when verifying version-specific claims</rule>
<rule>Cross-reference disputed claims with multiple sources</rule>
</rules>
<constraints>
<must>Query authoritative sources before verification</must>
<must>Document evidence for all verification results</must>
<must>Flag discrepancies with confidence scores</must>
<avoid>Marking claims verified without source check</avoid>
<avoid>Verifying claims based on assumption or memory</avoid>
<avoid>Ignoring version context in verification</avoid>
</constraints>
<related_skills>
<skill name="context7-usage">Core tool for library documentation verification</skill>
<skill name="investigation-patterns">Evidence collection methodology</skill>
<skill name="technical-documentation">Documentation accuracy standards</skill>
</related_skills>