Problem
Not all sources are equal. A court filing is more reliable than an anonymous tip. Source reliability should inform claim confidence and investigation quality metrics.
Scope
Source Tier System
| Tier | Reliability | Examples |
|------|-------------|----------|
| 1 | High | Court filings, official records, financial disclosures, FOIA responses, corporate registries |
| 2 | Medium | Major news outlets, academic papers, public statements, congressional testimony |
| 3 | Low | Social media, anonymous tips, single-source reports, opinion pieces |
Integration Points
`document_source.reliability` field maps to tiers
Claim confidence auto-calculation uses source tiers
QA metrics: percentage of claims backed by tier-1 sources
Investigation quality score: weighted average of source reliability across all claimsQA Rules
Warning: investigation with <20% tier-1 sources
Warning: claim marked `corroborated` but only has tier-3 sources
Info: source reliability distribution per investigationAcceptance Criteria
Source tiers configurable per KB (override defaults in kb.yaml)
Claim confidence calculation incorporates source tiers
QA reports source tier distribution
`investigation_sources` MCP tool filters by reliability