Conciseness

The body is almost entirely operational content — commands, tables, and harness code — with no explanation of concepts Claude already knows; even the prose asides carry non-obvious value ('Do NOT combine MSan with ASan — they conflict', '5–50 seeds beats 5000 random bytes'). Every token earns its place, matching the lean anchor.

Actionability

Build, run, and triage commands plus complete C harness skeletons are largely copy-paste ready, but there are minor gaps: the inline '# timeout per testcase (ms)' comment after a backslash continuation in the afl-fuzz command is broken shell syntax, and 'validate_workspace_finding' in section 10 is invoked without being defined or located anywhere in the skill.

Workflow Clarity

A clean ten-step sequence (scoping → fuzzer selection → instrumented build → harness → corpus → run → triage → exploitability → persist evidence) with explicit validation checkpoints: crash reproduction commands, afl-tmin minimization, backtrace-hash dedup, and a positive-signal/negative-control validation gate before reporting a finding. This matches the anchor with explicit validation steps and feedback loops.

Progressive Disclosure

The single ~260-line file is well-sectioned and self-contained (no bundle files exist to reference), but content such as the Tools Quick Reference table, the ASan bug-class table, and the exploitability rubric is inline material that would fit one-level-deep reference files — good structure with minor organization gaps rather than the well-signaled-references anchor.

Specificity

The description lists seven concrete, tool-specific actions — 'target scoping, fuzzer selection (AFL++/libFuzzer/Honggfuzz), harness skeleton, ASan+UBSan flags, corpus curation, crash triage and minimization (afl-tmin/minimize_corpus), exploitability rubric' — giving comprehensive coverage of the skill's capabilities, matching the top anchor rather than the 'minor gaps' anchor below it.

Completeness

It explicitly answers 'what' (the full capability list plus the output location 'Outputs corpora and crashes to /workspace/') and 'when' ('Triggers on: ...' with concrete trigger phrases), matching the anchor requiring both with concrete triggers rather than the anchor where 'when' could be more explicit.

Trigger Term Quality

The trigger list 'fuzz', 'fuzzing', 'AFL', 'libFuzzer', 'harness', 'crash triage', 'coverage-guided', 'afl-tmin', 'sanitizer', 'corpus' covers the natural phrases users would say, but a few obvious synonyms (e.g., 'afl++', 'asan', 'ubsan', 'honggfuzz') are missing from the triggers — the anchor for good coverage with a few natural terms missing.

Distinctiveness Conflict Risk

A clear niche — coverage-guided fuzzing of compiled binaries and libraries — with distinct, domain-specific triggers ('afl-tmin', 'coverage-guided', 'crash triage') that are unlikely to fire for unrelated skills, matching the minimal-conflict-risk anchor.