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 luabagg/agent-skills --skill testing-business-rulesgit clone --depth 1 https://github.com/luabagg/agent-skillsWrote 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/luabagg/agent-skills/testing-business-rules)<a href="https://agentmods.dev/skills/luabagg/agent-skills/testing-business-rules"><img src="https://agentmods.dev/badge/skills/luabagg/agent-skills/testing-business-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/luabagg/agent-skills/testing-business-rules"><img src="https://agentmods.dev/badge/skills/luabagg/agent-skills/testing-business-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 | $0.00045 | $0.01233 |
| Opus 5.5 | $0.00018 | $0.00493 |
| Sonnet 5.5 | $0.00009 | $0.00247 |
| Haiku 4.5 | $0.00005 | $0.00123 |
Grade A, and why
testing-business-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 19d 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 — 90 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Testing Business Rules
A test earns its place by protecting a meaningful behavior or contract, not by demonstrating today's implementation. A rule can be a product decision, a technical guarantee, or a consumer expectation.
Quick reference
| Keep coverage for | Reject or reshape |
|---|---|
| Domain behavior, API/provider contracts, numeric or ordering guarantees | Assertions that merely restate the implementation |
| Validation, authorization, privacy, data integrity | Input permutations with no distinct risk |
| Idempotency, retries, discard policies, persistence and queue integration | Private helper calls or incidental call order |
| Observed regressions, including obvious mistakes | Duplicate coverage with no additional failure detection |
| Boundaries with a named consequence | Snapshots that freeze incidental output |
Currency rounding can be a contract even when it uses simple arithmetic. Coverage metrics reveal gaps; they do not justify tests.
Procedure
1. Name the rule before writing the test
Record these in the test plan or review, not as boilerplate comments:
Rule: an empty tenant ID must never grant access to another tenant's records.
Established in: tenant-isolation security contract.
Failure: a caller reads another tenant's private records.
Find evidence in requirements, API documentation, callers, history, or incidents, not current output alone. Missing evidence requires investigation with owners and consumers, not coverage removal. Temporary characterization tests can support legacy refactoring; label unconfirmed assumptions instead of declaring permanent contracts.
2. Find the coverage gap
Identify the wrong behavior this test would catch. Compare failure modes, not lines executed: happy-path coverage does not cover an authorization bypass.
Keep regressions that protect valid rules and add detection, including obvious mistakes, manually detectable bugs, and bad decisions.
3. Choose the smallest honest boundary
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.
- 19d ago Changed · +2 lines eeacaf3f3bfb
- 24d ago First seen · 88 lines · 45 tokens per session scan A 57a1d46ba095
testing-business-rules is a skill published in the GitHub repository luabagg/agent-skills (3 stars, last pushed 12d ago), licensed MIT. It adds 45 tokens to every session and 1,233 once invoked, 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 2026-09-23.
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