Borrowing it
Nothing to install: this file belongs to axiomantic/spellbook. 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/axiomantic/spellbook/main/CLAUDE.mdgit clone --depth 1 https://github.com/axiomantic/spellbookWrote 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/axiomantic/spellbook/claude-md)<a href="https://agentmods.dev/instructions/axiomantic/spellbook/claude-md"><img src="https://agentmods.dev/badge/instructions/axiomantic/spellbook/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/axiomantic/spellbook/claude-md"><img src="https://agentmods.dev/badge/instructions/axiomantic/spellbook/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 | $0.00058 | $0.00058 |
| Opus 5.5 | $0.00023 | $0.00023 |
| Sonnet 5.5 | $0.00012 | $0.00012 |
| Haiku 4.5 | $0.00006 | $0.00006 |
Grade A, and why
spellbook 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 1mo 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.
What it actually says
Spellbook Development
Read and follow the instructions in AGENTS.md.
PR Review Bot
- Bot username: axiomantic-momus[bot]
- Re-review comment: /ai-review
- Auto-reviews on PR creation: no
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.
- 1mo ago First seen · 9 lines · 58 tokens per session scan A 3980cdd5c565
spellbook CLAUDE.md is an instructions file published in the GitHub repository axiomantic/spellbook (10 stars, last pushed 3d ago), licensed MIT. It adds 58 tokens to every session, about $0.0002 per session on Opus 5.5. 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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