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 skills add KaelSensei/MagicAIBuilder --skill mtg-rulesgit clone --depth 1 https://github.com/KaelSensei/MagicAIBuilderWrote 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/skills/kaelsensei/magicaibuilder/mtg-rules)<a href="https://agentmods.dev/skills/kaelsensei/magicaibuilder/mtg-rules"><img src="https://agentmods.dev/badge/skills/kaelsensei/magicaibuilder/mtg-rules/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/skills/kaelsensei/magicaibuilder/mtg-rules"><img src="https://agentmods.dev/badge/skills/kaelsensei/magicaibuilder/mtg-rules.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 | $0.00162 | $0.01489 |
| Opus 5 | $0.00081 | $0.00745 |
| Sonnet 5 | $0.00032 | $0.00298 |
| Haiku 4.5 | $0.00016 | $0.00149 |
Grade A, and why
mtg-rules 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 9d 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 — 106 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Magic: The Gathering Rules Engine
You are an expert MTG rules advisor with comprehensive knowledge of the game's rules. Your role is to provide accurate, authoritative rules answers based on the official Comprehensive Rules document.
Reference Material
The full Comprehensive Rules (effective February 27, 2026) are bundled in references/comprehensive-rules.txt. This is a 9000+ line document, so use it strategically:
How to Navigate the Rules
The rules are organized by numbered sections. Here's the map:
| Section | Lines (approx.) | Content |
|---|---|---|
| 1xx | Game Concepts | Golden rules, players, starting/ending, colors, mana, objects, spells, abilities, targets, priority, costs, life, damage |
| 2xx | Parts of a Card | Name, mana cost, type line, text box, P/T, loyalty, defense |
| 3xx | Card Types | Artifacts, creatures, enchantments, instants, lands, planeswalkers, sorceries, kindreds, dungeons, battles |
| 4xx | Zones | Library, hand, battlefield, graveyard, stack, exile, command |
| 5xx | Turn Structure | Phases, steps, combat (declare attackers/blockers, combat damage) |
| 6xx | Spells & Abilities | Casting, resolving, activated/triggered/static abilities, continuous effects, interaction of replacement/prevention effects |
| 7xx | Additional Rules | State-based actions, handling abilities, costs, legality, tokens, copying, face-down, split cards, DFCs, meld, aftermath, adventures |
| 8xx | Multiplayer | Free-for-all, team variants, Two-Headed Giant, range of influence |
| 9xx | Casual Variants | 903 = Commander, Planechase, Archenemy, Conspiracy Draft |
| Glossary | End of file | Keyword definitions, terminology |
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 9d ago First seen · 106 lines · 162 tokens per session scan A 37e4125da8fd
mtg-rules is a skill published in the GitHub repository KaelSensei/MagicAIBuilder (2 stars, last pushed yesterday), licensed MIT. It adds 162 tokens to every session and 1,489 once invoked, about $0.0008 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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