B
Evidence Grade B
Graded
accuracy verified by the review judge
Safe to Cite
Current
48%
48% -- defect detection rate for Vanilla Claude Code (no skill) (2026-07-07)
Vanilla Claude Code achieved a 48% defect detection rate on the seo-skill-bench benchmark prior to the harness bug fix.
- Pre-bug-fix score suppressed by a benchmark harness bug that caused live site fetches to time out
Attribution:
View source
Lighthouse Research Team
Last verified:
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Source verified
Evidence graded
Value
48%
Unit
Percentage
Data Vintage
2026-07-07
Entity
Sample Size
10
Evidence Quality
B
Strong, reliable evidence
Sourced from a well-regarded research firm or industry leader with transparent methodology and a reasonably large sample.
Single source - not yet corroborated
Score breakdown
Extraction
95
Source Trust
60
Citation Chain
20
Independence
30
Methodology
45
Freshness
95
Source
SEOAgent
Primary
Tier A
https://seoagent.com/blog/best-free-claude-seo-skill ↗
Source Article
Best Claude SEO Skill? An Open Benchmark (2026)
Which Free Claude SEO Skill Is Best? We Built an Open Benchmark — and Our Own Skill Came Last
Star counts don't measure whether an SEO skill gives correct advice. So we built an open benchmark with planted-defect answer keys — and published everything, including the runs where our own skill finished…
Original Research
SEOAgent
· Original study ↗
Methodology
Same-day full-fleet rerun after harness bug fix; range 48%-71%, midpoint not used, post-fix value extracted
Methodology documented
Segmentation
Industrymarketing
Cite this stat
Plain Text
Vanilla Claude Code (no skill): 48% defect detection rate. Source: SEOAgent (2026-07-07). Via Lighthouse Intelligence -- https://lighthousedata.io/data/harness-bug-vanilla-detection-48-71
HTML Embed
<blockquote cite="https://lighthousedata.io/data/harness-bug-vanilla-detection-48-71" style="border-left:3px solid #2563eb;padding:12px 16px;margin:16px 0;font-family:system-ui,sans-serif;background:#f0f4ff;"><strong>48%</strong> -- defect detection rate for Vanilla Claude Code (no skill)<br><small>Source: SEOAgent (2026-07-07) · <a href="https://lighthousedata.io/data/harness-bug-vanilla-detection-48-71" target="_blank" rel="noopener">Lighthouse Intelligence</a></small></blockquote>
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