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 aegntic/cldcde --skill ae-ltd-mutation-gategit clone --depth 1 https://github.com/aegntic/cldcdeWrote 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/aegntic/cldcde/ae-ltd-mutation-gate)<a href="https://agentmods.dev/skills/aegntic/cldcde/ae-ltd-mutation-gate"><img src="https://agentmods.dev/badge/skills/aegntic/cldcde/ae-ltd-mutation-gate/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/aegntic/cldcde/ae-ltd-mutation-gate"><img src="https://agentmods.dev/badge/skills/aegntic/cldcde/ae-ltd-mutation-gate.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 | $0.00042 | $0.00346 |
| Opus 5.5 | $0.00017 | $0.00138 |
| Sonnet 5.5 | $0.00008 | $0.00069 |
| Haiku 4.5 | $0.00004 | $0.00035 |
Grade A, and why
ae-ltd-mutation-gate 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 today.
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
AE.LTD Mutation Gate
What This Skill Does
Measures test quality beyond line coverage using mutation testing. Exposes weak assertions and generates actionable test hardening recommendations. Niche gem source: mutation-tester plugin from awesome-claude-code-toolkit.
- Detect appropriate mutation tool (Stryker/mutmut/PIT)
- Run targeted mutation tests on critical modules
- Convert survived mutants into hardened tests
- Track mutation score to threshold (target: 80%+)
Quick Start
User: "My tests pass but I'm not confident"
→ Detect stack → Run mutations → Report survivors → Harden tests
Workflow
- Detect stack and tool.
- JS/TS: Stryker
- Python: mutmut
- Java: PIT
-
Start narrow. Run mutation testing on one critical module first to keep runtime bounded.
-
Measure score and survivors. Capture killed/survived/timed-out mutants and mutation score.
-
Convert survivors into tests. For each top survived mutant, specify the exact missing assertion and test case.
-
Re-run until stable threshold. Target at least 80% mutation score unless user/project standard says otherwise.
Guardrails
- Exclude generated files and non-business logic.
- Use per-mutant timeouts to control runaway test runs.
- Report equivalent-mutant risk explicitly.
- Prioritize critical-path business logic over utility files.
What ships with it
2 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.
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.
- today First seen · 49 lines · 42 tokens per session scan A 9732d7146890
ae-ltd-mutation-gate is a skill published in the GitHub repository aegntic/cldcde (11 stars, last pushed today), licensed MIT. It adds 42 tokens to every session and 346 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 2026-11-05.
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