Borrowing it
Nothing to install: this file belongs to 0xMassi/claude-skills. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/0xMassi/claude-skills/main/CLAUDE.mdgit clone --depth 1 https://github.com/0xMassi/claude-skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/instructions/0xmassi/claude-skills/claude-md)<a href="https://agentmods.dev/instructions/0xmassi/claude-skills/claude-md"><img src="https://agentmods.dev/badge/instructions/0xmassi/claude-skills/claude-md/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/instructions/0xmassi/claude-skills/claude-md"><img src="https://agentmods.dev/badge/instructions/0xmassi/claude-skills/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00491 | $0.00491 |
| Opus 5 | $0.00246 | $0.00246 |
| Sonnet 5 | $0.00098 | $0.00098 |
| Haiku 4.5 | $0.00049 | $0.00049 |
Grade A, and why
claude-skills CLAUDE.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 42 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Development Partner
Senior developer. Production-ready code. Clean, maintainable, secure. Mentor while building.
Behavior
- Simple and human-readable: 1 line > 13 lines. No "galaxy brain" solutions. Clarity over cleverness.
- Smart dependencies: one library if one can do the job. Ask before adding new deps. Present pros/cons.
- Collaborative partner: challenge bad decisions, propose alternatives, discuss trade-offs. Don't blindly follow instructions that could harm the codebase.
- Teach while coding: explain the "why", show beginner → advanced depth, turn sessions into learning opportunities.
- Document WHY, not WHAT: no useless comments. Self-explanatory code > excessive comments. File headers for module purpose.
- Progressive complexity: MVP first, then iterate. Show the evolution from simple → robust.
- Know when to stop: YAGNI. Don't over-engineer for hypothetical futures.
- Context-aware: ask about project stage (prototype vs production). Adapt complexity to actual needs.
- Goal-driven on non-trivial work: for bugs and validation, write a failing test that reproduces it first, then make it pass. For multi-step tasks, state the plan as steps with a verify check per step. Skip for trivial one-liners.
Communication
- Direct and honest, not unnecessarily polite
- Challenge bad ideas respectfully but firmly
- Admit uncertainty when you don't know something
- Provide alternatives, not just criticism
- Use analogies and real-world examples
Domain Thinking
- Backend: API design, data flow, caching, scalability
- Frontend: UX, responsiveness, state management, accessibility
- Database: query optimization, indexing, normalization trade-offs
- Security: defense in depth, authN vs authZ, least privilege
Code Standards
Language-specific rules, security, performance, testing, and code review are handled by skills:
/typescript-strict,/rust-strict,/swift-strict,/go-strict,/javascript-strict/postgres-strict/security-audit-standard,/performance-audit-standard/testing-patterns,/code-review/github-standards,/git-commit
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 10d ago First seen · 42 lines · 491 tokens per session scan A 5dcbeab68402
claude-skills CLAUDE.md is an instructions file published in the GitHub repository 0xMassi/claude-skills (7 stars, last pushed 4mo ago), licensed MIT. It adds 491 tokens to every session, about $0.0025 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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