Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add instructions/axiomantic/spellbook/agents-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/agents-md)<a href="https://agentmods.dev/instructions/axiomantic/spellbook/agents-md"><img src="https://agentmods.dev/badge/instructions/axiomantic/spellbook/agents-md.svg" alt="Measured on agentmods" 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 | $0.07589 | $0.07589 |
| Opus 5 | $0.03794 | $0.03794 |
| Sonnet 5 | $0.01518 | $0.01518 |
| Haiku 4.5 | $0.00759 | $0.00759 |
Grade A, and why
spellbook AGENTS.md scanned grade A with 2 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 3d 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.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
- **Root** `install.py` (the curl-pipe target, documented entry) — handles fresh installs and upgrades via `python3 install.py`. Runs shell commandslowCapability
Expected in a hook, worth knowing in a rule or an instructions file.
# This test is now allowed to use subprocess.run/Popen How it starts
The opening of the file, as written. The whole thing — 545 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Spellbook Development
Quick Start
# Install dependencies
uv pip install -e ".[dev,test]"
# Run tests (targeted)
uv run pytest tests/test_specific_file.py -x
# Run fast tests (default - skips docker, integration, slow, external)
uv run pytest tests/ -x
# Run ALL tests including slow/integration (as CI does)
uv run pytest tests/ -x --override-ini="addopts=" -m "not docker"
# Run linting
uv run ruff check .
# Generate documentation (pre-commit only checks freshness; run this yourself)
uv run scripts/generate_docs.py
Session Start: Pre-release Check
On session start in this project, check if there's a GitHub pre-release newer than the latest full release:
gh release list --limit 5 --repo axiomantic/spellbook
If a pre-release exists that is newer than the last actual release, ask: "There's a pre-release (vX.Y.Z) ready. Want to promote it to a full release?"
Key Conventions
- AGENTS.md (this file) is for working on the spellbook repo itself. Only update it when changing the development workflow for this specific project (build commands, test conventions, architecture notes). It is NOT installed anywhere.
rules/*.mdare the global user-facing rule modules that the spellbook installer ships. Directory-capable platforms receive one symlink per selected module in the platform's rules directory (~/.claude/rules/for Claude Code); flat platforms receive a generated concatenation at their real instruction path. Each module carries YAML frontmatter (id,class,default,benefit) and holds global directives, instructions, and behavioral rules that apply to ALL projects. This is where cross-project instructions belong.- Editing an existing
rules/*.mdfile takes effect immediately on directory-capable platforms — the installed file is a symlink to the source, so no reinstall step is needed. - Adding a NEW file under
rules/does need a step: runuv run install.pyto create its symlink (or regenerate the flat-platform concatenation) before the new module reaches any installed platform.MANIFEST.mddoes not trackrules/*.md— it only registers skills, commands, and agents — so there is no manifest entry to add for a new rule module, just the install step.
- Editing an existing
- Skills go in
skills/<name>/SKILL.mdwith YAML frontmatter - Commands go in
commands/<name>.mdwith YAML frontmatter - Hooks go in
hooks/and must be registered ininstaller/components/hooks.py - MCP tools are defined in
spellbook/mcp/server.pyandspellbook/mcp/tools/modules
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.
- 3d ago First seen · 545 lines · 7,589 tokens per session scan A e6238b7fccfa
spellbook AGENTS.md is an instructions file published in the GitHub repository axiomantic/spellbook (10 stars, last pushed yesterday), licensed MIT. It adds 7,589 tokens to every session, about $0.0379 per session on Opus 5. A static security scan graded it A with 2 findings (makes network calls, runs shell commands). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
Other instructions, from other repositories
awesome-cursorrules-zh copilot-instructions.md
Copilot instructions for holtwood/awesome-cursorrules-zh, covering github copilot instructions, 项目概述, 技术栈, 代码规范 and 提交格式.
awesome-skills CLAUDE.md
Claude Code instructions for johnqtcg/awesome-skills, covering claude.md, what this repo is, skill structure convention, running regression tests and or with coverage.
nextjs-skills CLAUDE.md
Instructions for mohamed-hossam1/nextjs-skills: All contribution rules — style, naming, file layout, verification — live in AGENTS.md. Read that first.
claude-plugins CLAUDE.md
Claude Code instructions for aiocean/claude-plugins, covering claude.md, what this is, plugin structure, marketplace registry and plugin categories.
cursorrules-pro copilot-instructions.md
Copilot instructions for Wittlesus/cursorrules-pro, covering github copilot instructions — backend api, project context, code generation rules, architecture layers and consistent response format.
vscode buildNext.instructions.md
Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).