Problem
Investigations accumulate unverified claims. A fact-checker agent skill can systematically evaluate claims, search for corroborating or contradicting evidence, and update claim status — maintaining the evidence chain throughout.
Scope
Claude Code skill for claim verification
Input: claim ID or batch of unverified claims
Process: read claim → search for corroborating sources → evaluate evidence → update claim status
Creates: evidence entries linked to source documents
Updates: claim status (unverified → partially_verified → corroborated/disputed)
Updates: claim confidence based on evidence quality
Flags: claims that cannot be verified (insufficient evidence)
Cross-reference: checks if other claims in the KB contradictAcceptance Criteria
Skill evaluates claims and produces evidence entries with source links
Claim status updated through proper lifecycle transitions
Evidence chains are complete: claim → evidence → source_document
Cross-claim contradiction detection works
Session logged with verification methodology and limitations