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 JordanCoin/codingskills --skill law-of-demetergit clone --depth 1 https://github.com/JordanCoin/codingskillsWrote 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/jordancoin/codingskills/law-of-demeter)<a href="https://agentmods.dev/skills/jordancoin/codingskills/law-of-demeter"><img src="https://agentmods.dev/badge/skills/jordancoin/codingskills/law-of-demeter/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/jordancoin/codingskills/law-of-demeter"><img src="https://agentmods.dev/badge/skills/jordancoin/codingskills/law-of-demeter.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 | $0.00059 | $0.01152 |
| Opus 5 | $0.00030 | $0.00576 |
| Sonnet 5 | $0.00012 | $0.00230 |
| Haiku 4.5 | $0.00006 | $0.00115 |
Grade A, and why
law-of-demeter 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 12d 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 — 88 lines — stays where its author put it; the contents beside it link to each section on GitHub.
LoD — Law of Demeter (Principle of Least Knowledge)
Before Applying
If .agents/stack-context.md exists, read it first. Apply this principle using idiomatic patterns for the detected stack. For framework-specific details, use context7 MCP or web search — don't guess.
Principle
A component should only talk to its immediate collaborators. Don't reach through an object to access its internals, its children's internals, or anything deeper.
More precisely: a method should only call methods on (1) itself, (2) its own fields, (3) its parameters, (4) objects it creates, and (5) global/singleton services.
Why This Matters in Production
Every chain of access (order.customer.address.city) is a chain of coupling. If any link in that chain changes — the customer model gets restructured, address becomes optional, city moves to a sub-object — every caller breaks.
LoD violations create fragile systems where a seemingly small refactor triggers cascading failures across unrelated code. They also make testing painful: to test a function that reaches through 4 layers, you must mock all 4 layers.
In production, LoD violations are a leading cause of NullPointerException and undefined is not an object errors. Each . in a chain is a potential null/undefined dereference point.
Rules
- Don't chain through objects. If you need data from deep inside a structure, ask the immediate owner to provide it.
order.shipping_city()notorder.customer.address.city. - Tell, don't ask. Instead of reaching into an object to get data and make a decision, tell the object what you need done. Let it use its own internals.
- Wrap external APIs at the boundary. Third-party SDKs and API responses often expose deep structures. Create a thin wrapper that exposes only what your code needs, in the shape your code needs.
- Flatten data for consumers. When passing data across boundaries (to templates, to frontends, to other services), flatten the nested structure into a purpose-built shape rather than exposing your internal model.
- Limit parameter knowledge. A function that receives an object should only use the fields it directly needs. If it only needs the user's email, accept the email — not the entire user object.
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.
- 12d ago First seen · 88 lines · 59 tokens per session scan A eb19648bca6b
law-of-demeter is a skill published in the GitHub repository JordanCoin/codingskills (7 stars, last pushed 6mo ago), licensed MIT. It adds 59 tokens to every session and 1,152 once invoked, about $0.0003 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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