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testland/mull-mutation

Runs Mull, the LLVM-IR mutation testing tool, against C/C++ test binaries built with Clang: covers install (the version-matched mull-NN package), the -fpass-plugin build flags for the Mull IR frontend, mull-runner invocation, the mutator catalog, path filtering, and GitHub Actions CI. Use when a C or C++ project needs mutation-score verification with the tool already chosen. Does not select among mutation tools and does not cover other languages (stryker-mutation for JS/TS, stryker-net-mutation for .NET, pitest-mutation for the JVM, mutmut-mutation for Python).

73

Quality

92%

Does it follow best practices?

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SecuritybySnyk

Passed

No findings from the security scan

Overview
Quality
Evals
Security
Files

Quality

Content

80%

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

The body is highly actionable and concise with a clean 7-step sequence, but it lacks explicit validation checkpoints for its batch mutation runs and keeps all detail inline rather than progressively splitting longer sections into references.

Suggestions

Add an explicit validation checkpoint after the build step (e.g., confirm the binary was instrumented and that the mull-NN suffix matches clang-NN before running) to support a verify-and-retry feedback loop.

Split the mutator catalog and/or the CI integration section into reference files with one-level-deep links from the main body, tightening the core workflow.

Consolidate the repeated 'per [mull-readme][mr]' citations in the Overview to reduce token redundancy.

DimensionReasoningScore

Conciseness

Lean and efficient with tight sectioned content that assumes Claude's competence; it avoids explaining what mutation testing or LLVM is, and nearly every token earns its place despite minor README-quote redundancy.

3 / 3

Actionability

Fully executable throughout — concrete CMake flags (-fpass-plugin=/usr/lib/mull-ir-frontend-19), exact mull-runner-19 invocations, a concrete mutator table, filtering commands, and a copy-paste CI YAML snippet.

3 / 3

Workflow Clarity

The 7-step sequence is clearly ordered, but the workflow involves a risky batch operation with no explicit validation/feedback checkpoint (e.g., verify mull-NN matches clang-NN before building, or confirm an instrumented binary was produced), capping it at 2.

2 / 3

Progressive Disclosure

The single-file skill is well-organized with clearly signaled one-level-deep external URL references, but at ~200 lines it keeps content that could be split (mutator catalog, CI integration) inline rather than progressive, so structure is good but not maximally separated.

2 / 3

Total

10

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12

Passed

Description

100%

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

The description is strong across all dimensions: specific, third-person, with explicit use-when triggers and clear conflict-avoidance boundaries against sibling mutation tools. No changes needed.

DimensionReasoningScore

Specificity

Lists multiple concrete actions — install (version-matched mull-NN package), -fpass-plugin build flags, mull-runner invocation, mutator catalog, path filtering, and GitHub Actions CI — matching the score-3 anchor.

3 / 3

Completeness

Explicitly answers both what (runs Mull across install/build/runner/mutators/filtering/CI) and when ('Use when a C or C++ project needs mutation-score verification with the tool already chosen'), matching the score-3 anchor.

3 / 3

Trigger Term Quality

Natural terms a user would say are well covered ('mutation testing', 'mutation-score verification', 'C/C++', 'GitHub Actions CI'), matching the score-3 anchor for good natural-term coverage.

3 / 3

Distinctiveness Conflict Risk

Clear niche (Mull + C/C++ + LLVM-IR) with explicit negative scope naming the sibling skills it is NOT (stryker, pitest, mutmut), giving distinct triggers unlikely to conflict.

3 / 3

Total

12

/

12

Passed

Validation

100%

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

Validation16 / 16 Passed

Validation for skill structure

No warnings or errors.

Reviewed

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