evaluation-justification-before-score-prevents-anchoring-bias

Requiring written justification before assigning a numeric score prevents anchoring bias in evaluations — the score adjusts to match the justification rather than the justification being retrofitted to a gut-feel score. A pairwise double-pass (evaluate A vs B, then B vs A independently) catches directional bias where the first option evaluated receives a structural advantage. This applies to all scored evaluations: skill quality, MCP tool quality, PR review scores.