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antithesis-mutation-testing

Validate that an Antithesis property catalog can actually catch bugs. For each safety property, inject one realistic mutant into the SUT, run it, and confirm the targeted property fires. Diagnoses survivors as a bad mutant, bad oracle, bad workload, or bad property, and routes fixes back to antithesis-workload or antithesis-research. Use once the harness is built and a baseline run is green.

Quality

91%

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SecuritybySnyk

Low

Low-risk findings worth noting

SKILL.md
Quality
Evals
Security

Quality

Content

88%Weight 40%Scale 1-5

Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.

An exceptionally well-engineered orchestration skill: concrete commands and thresholds everywhere, rigorously sequenced workflows with validation at every spend-point, and a well-wired one-level-deep reference bundle. The only real costs are redundancy across the interview/iterate/self-review sections and a body that carries more inline edge-case detail than a lean overview would.

Suggestions

Consolidate the repeatedly-stated authorization rules (interview question 4, run ceiling, two-branch rule) into one canonical section and reference it from Purpose, Iterate, and Self-Review instead of restating them in each place.

Move the baseline-gate edge-case taxonomy (counterexample_count logic, fallback-SDK/JavaScript cataloging exceptions, Python instrumentation caveat) into references/sweep-and-verdicts.md or references/catalog-reconstruction.md, keeping in the body only the gate's pass/fail decision rule.

Trim the Self-Review checklist to items not already enforced inline at the workflow step where they apply (e.g., announcement verification and history.md rows are already mandated in the First sweep steps), reducing body length without losing coverage.

DimensionReasoningScore

Conciseness

Efficient and dense — it assumes competence (no generic mutation-testing or git/docker explanations) and confines definitions to Antithesis-specific concepts — but the interview-question-4/ceiling rules, clean.sh caveats, and Self-Review checklist restate constraints already given in earlier sections, so some trimming is possible.

4 / 5

Actionability

Consistently executable guidance: named scripts with roles (sync-patches.sh, verify-mutant.sh, select-mutant.sh), exact artifact paths, exact flags (--source, --ephemeral), exact version thresholds ("snouty older than 0.8.0"), a named verdict taxonomy, and explicit skill routing ("do not run snouty launch directly") — no meaningful gaps for an instruction-orchestration skill.

5 / 5

Workflow Clarity

Three fully sequenced workflows (14-step first sweep, iterate, resume) with explicit validation checkpoints throughout — baseline gate before mutant design, verify-mutant.sh and announcement checks before launch, static validation before spending runs, clean.sh confirming no residue — plus feedback loops for error recovery and a Self-Review checklist, fully satisfying the batch-operation validation requirement.

5 / 5

Progressive Disclosure

Good bundle structure: a Reference Files table with when-to-read guidance, section-level pointers into seven real (verified) reference files, and executable harness assets one level deep. Held at 4 because the ~300-line body inlines detailed edge-case taxonomy (counterexample_count logic, fallback-SDK/JavaScript exceptions, instrumentation caveats) that could live in a reference, and reference files cross-point to one another.

4 / 5

Total

18

/

20

Passed

Description

92%Weight 40%Scale 1-5

Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.

A highly effective description: concrete, third-person, multi-action capability statement with an explicit use-when precondition and clean separation from sibling skills. Only minor keyword-synonym coverage is missing.

DimensionReasoningScore

Specificity

Lists multiple specific concrete actions — "inject one realistic mutant into the SUT, run it, and confirm the targeted property fires" plus a complete survivor-diagnosis taxonomy ("bad mutant, bad oracle, bad workload, or bad property") and explicit fix routing — with no coverage gaps, matching the comprehensive anchor.

5 / 5

Completeness

Explicitly answers both questions: the "what" is multi-part (inject, run, confirm the property fires, diagnose survivors, route fixes) and the "when" is an explicit trigger clause — "Use once the harness is built and a baseline run is green" — stated as a concrete precondition rather than implied.

5 / 5

Trigger Term Quality

Good natural keyword coverage for the domain ("Antithesis property catalog", "catch bugs", "safety property", "mutant", "survivors", "baseline run is green"), but a few natural terms are missing — "mutation testing" itself appears only in the name, and synonyms like "kill mutants" or "oracle validation" are absent — so it is not fully comprehensive.

4 / 5

Distinctiveness Conflict Risk

Occupies a clear niche (validating the Antithesis oracle via mutation testing) and explicitly delineates boundaries by routing fixes to sibling skills ("antithesis-workload or antithesis-research"), making wrong-skill triggering unlikely.

5 / 5

Total

19

/

20

Passed

Validation

93%

Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.

Validation — 15 / 16 Passed

Validation for skill structure

CriteriaDescriptionResult

referenced_paths_exist

Referenced path issues: 2 missing

Warning

Total

15

/

16

Passed

Repository

antithesishq/antithesis-skills

Path

antithesis-mutation-testing/SKILL.md

Reviewed

Table of Contents

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