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 AuraVixStudio/caelo --skill write-testsgit clone --depth 1 https://github.com/AuraVixStudio/caeloWrote 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/auravixstudio/caelo/write-tests)<a href="https://agentmods.dev/skills/auravixstudio/caelo/write-tests"><img src="https://agentmods.dev/badge/skills/auravixstudio/caelo/write-tests/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/auravixstudio/caelo/write-tests"><img src="https://agentmods.dev/badge/skills/auravixstudio/caelo/write-tests.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 | $0.00020 | $0.00269 |
| Opus 5.5 | $0.00008 | $0.00108 |
| Sonnet 5.5 | $0.00004 | $0.00054 |
| Haiku 4.5 | $0.00002 | $0.00027 |
Grade A, and why
Write tests 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 1mo 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.
What it actually says
Write tests
Use this when code needs tests. Aim for tests that would actually catch a regression, not just raise the coverage number.
Steps
- Locate the harness. Find how tests are run and structured (test dir, framework, naming). Match it — do not introduce a new framework.
- Identify behavior. List the function/module's contracts: expected output, error cases, boundaries (empty, null, large, malformed input).
- Write tests. One assertion-focused test per behavior. Cover the happy path first, then the edge cases you listed. Name each test after the behavior it pins.
- Run them. Execute the suite. Confirm the new tests pass and that they fail if you break the code (a test that can't fail is worthless).
- Report. Summarize what is now covered and any behavior you deliberately left untested.
Notes
- Prefer real assertions over snapshot dumps. Keep each test independent.
- Test behavior, not implementation details — so refactors don't break the tests.
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.
- 1mo ago First seen · 28 lines · 20 tokens per session scan A 6253ca2a09ca
Write tests is a skill published in the GitHub repository AuraVixStudio/caelo (25 stars, last pushed 9d ago), licensed Apache-2.0. It adds 20 tokens to every session and 269 once invoked, about $0.0001 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 2026-08-30.
Other skills, from other repositories
test-fixture-designer
Use when the user asks to design, create, simplify, repair, or review test fixtures, factories, builders, seeded datasets, temporary files, or test environment setup. Produce minimal, explicit, isolated data that makes tests readable, deterministic, and safe to clean up.
unit-test-engineer
Use when the user asks to create, improve, review, or repair unit tests for a function, module, component, or isolated behavior. Derive observable contracts from real code, keep tests deterministic and focused, and use the repository's existing test runner and helpers.
error-collection
A structured record of confirmed engineering mistakes, their root causes, and checks that prevent them from returning. It uses evidence from real application behavior, not just successful builds.
contract-test-engineer
Use when the user asks to verify compatibility between an API provider and consumer, SDK and service, event producer and consumer, schema versions, or serialized data. Define and test the shared contract, including failures and compatibility rules, before changing either side.
e2e-test-engineer
Use when the user asks to create, improve, review, or repair end-to-end tests for a meaningful user workflow across the UI, runtime, backend, or installed application. Validate the real workflow at the highest useful boundary while keeping environments, accounts, and test data controlled.
flaky-test-triage
Use when a test passes and fails intermittently, behaves differently by order, machine, runtime, timing, or retry, or when the user asks to reduce test flakiness. Gather repeatable evidence, isolate nondeterminism, and repair the causal dependency without weakening test intent.