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 skills/millionco/expect/effect-best-practicesnpx skills add millionco/expect --skill effect-best-practicesgit clone --depth 1 https://github.com/millionco/expectWrote 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/millionco/expect/effect-best-practices)<a href="https://agentmods.dev/skills/millionco/expect/effect-best-practices"><img src="https://agentmods.dev/badge/skills/millionco/expect/effect-best-practices.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 | $0.00045 | $0.03463 |
| Opus 5 | $0.00023 | $0.01732 |
| Sonnet 5 | $0.00009 | $0.00693 |
| Haiku 4.5 | $0.00005 | $0.00346 |
Grade A, and why
effect-best-practices 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 4d 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.
The source is not reproduced here
No licence file
A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.
What ships with it
8 files 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.
- references/anti-patterns.md 7.8 KB
- references/effect-atom-patterns.md 13 KB
- references/error-patterns.md 14 KB
- references/layer-patterns.md 8.4 KB
- references/observability-patterns.md 8.7 KB
- references/rpc-cluster-patterns.md 11 KB
- references/schema-patterns.md 9.2 KB
- references/service-patterns.md 8.3 KB
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.
- 4d ago First seen · 445 lines · 45 tokens per session scan A 0c67c615159e
effect-best-practices is a skill published in the GitHub repository millionco/expect (3,552 stars, last pushed 4mo ago), with no licence file. It adds 45 tokens to every session and 3,463 once invoked, about $0.0002 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 2026-08-30.
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