Pull every README.md from every Opus 4.7 repo. Count the lines.
README length distribution
| Metric | Lines |
|---|---|
| Repos with README.md | 17,268 |
| Median length | 66 lines |
| p90 length | 267 lines |
| Max observed | 6,827 lines |
A 66-line median is substantial by open-source norms. Most GitHub READMEs are 10-40 lines (a title, a paragraph, some install commands). Opus 4.7’s are 50% longer.
What fills 66 lines
A typical Opus 4.7 README contains:
- Title + 1-2 sentence description
- Badges (build status, version, license)
- Features section (4-8 bullet points)
- Installation (clone + env setup)
- Usage (minimum viable example)
- Configuration (env vars, config file)
- Development (local setup, test commands)
- Project structure (directory tree)
- Deployment (if applicable)
- Contributing (rules, coding style reference)
- License
That’s the prose skeleton. A 66-line README fills most of these sections concisely.
The p90 at 267 lines
The top 10% of READMEs exceed 267 lines. These are the repos where README.md has become the primary user-facing documentation — think:
- elizaOS/eliza (agent framework docs embedded in README)
- Multi-part SDK repos with full API reference inline
- Platform starter kits with deployment guides
A 267-line README is essentially a documentation site collapsed into a single file. This is a conscious choice: Opus 4.7 tends to write one long README rather than a docs/ folder with many pages. That’s not universal — some repos have both — but the gravity is toward “comprehensive README.”
The 6,827-line outlier
The maximum we observed is a 6,827-line README. That’s longer than most technical books’ opening chapters.
When a README crosses 1,000 lines, it’s no longer documentation — it’s a book. Opus 4.7 doesn’t usually produce those, but a handful of maintainers clearly drive it toward that extreme.
Docs beyond README
This 66-line median is READMEs specifically. It’s separate from:
- CLAUDE.md (1,665 files across 1,324 repos) — the agent-facing prompt
- AGENTS.md (813 files) — multi-agent coordination
- TODO.md (97 files)
- docs/ folders — common in medium+ repos
Total markdown in the corpus: 110,506 files. 19% of all files in Opus 4.7 repos are markdown. Documentation is genuinely present.
Why it matters
READMEs are not just developer docs — they’re the agent context for the next session. When Claude Code re-opens a repo, it reads the README before touching source code. A 66-line README gives the model enough context to continue the project rather than re-learn it.
This is different from the human norm: humans rarely read 66 lines before coding. Agents do. Opus 4.7 is writing READMEs for its future self, as much as for human users.
The training signal
If you’re generating “build me X” output and want it to feel like Opus 4.7 idiomatic:
- Don’t produce a 10-line README. Produce a 60-80 line one that covers features, install, usage, dev, deploy, license.
- Structure it as H2 sections — H1 for title, H2 for each area (Install, Usage, etc.)
- Include a code example in the Usage section — every time
This matches the median Opus 4.7 shape almost exactly.
Next up: the licensing gap. READMEs are thorough; LICENSE files are almost always missing. Stay tuned.