Borrowing it
Nothing to install: this file belongs to JonJam/accuweather-mcp. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/JonJam/accuweather-mcp/main/.agents/skills/mutation-testing/SKILL.mdgit clone --depth 1 https://github.com/JonJam/accuweather-mcpWrote 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/jonjam/accuweather-mcp/mutation-testing)<a href="https://agentmods.dev/skills/jonjam/accuweather-mcp/mutation-testing"><img src="https://agentmods.dev/badge/skills/jonjam/accuweather-mcp/mutation-testing/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/jonjam/accuweather-mcp/mutation-testing"><img src="https://agentmods.dev/badge/skills/jonjam/accuweather-mcp/mutation-testing.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 | $0.00018 | $0.00251 |
| Opus 5.5 | $0.00007 | $0.00100 |
| Sonnet 5.5 | $0.00004 | $0.00050 |
| Haiku 4.5 | $0.00002 | $0.00025 |
Grade A, and why
mutation-testing 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 2mo 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
Mutation testing
Use this skill when you need to validate tests with mutation testing rather than relying on line coverage alone.
Workflow
- Run
./gradlew pitestfrom the repository root. - Open the HTML report at
build/reports/pitest/index.htmland review the XML report atbuild/reports/pitest/mutations.xml. - Focus on surviving mutants in classes
- Add or strengthen tests around edge cases such as null inputs, blank values, boundary lengths, and trimmed output.
- Remove or simplify tests that do not contribute to killing mutants or validating meaningful behaviour; mutation-testing results should guide whether a test is worth keeping.
- Re-run
./gradlew pitestuntil the configured mutation threshold is met.
Repository notes
- The project uses the Gradle PIT plugin configured in
build.gradle. - The mutation threshold is enforced through the
pitesttask, so a surviving mutant can fail the build if the score drops too low. - A test that only duplicates another assertion or provides no mutant-killing signal is a good candidate for cleanup.
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.
- 2mo ago First seen · 24 lines · 18 tokens per session scan A 4a0e3076c612
mutation-testing is a skill published in the GitHub repository JonJam/accuweather-mcp (0 stars, last pushed 4mo ago), licensed MIT. It adds 18 tokens to every session and 251 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 2026-08-31.
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