Conciseness

The body is lean and assumes Claude's competence — it never explains what cargokit or submodules are, and every section carries repo-specific knowledge (paths, commands, CI job names). It fits anchor 4 rather than 5 because the core three-layer distinction is restated across four sections (Overview, Mental Model, Common Mistakes, What To Say Explicitly), e.g. "a large cargokit diff in examples often does not mean FRB designed a large new cargokit behavior" reappears as "Assuming a large example diff implies a large semantic cargokit change" — minor redundancy that could be trimmed. It is far above anchor 3, which expects unnecessary explanation rather than strategic reinforcement.

Actionability

Guidance is fully concrete and executable: copy-paste commands ("./frb_internal sync-cargokit-copies", "./frb_internal generate-internal --set-exit-if-changed --coverage"), exact source-of-truth paths, the named CI job ("Generate :: Internal"), and an ordered diff procedure ("Compare the old and new submodule SHAs inside the submodule repository"). Per the rubric's scoring note for instruction-only skills, the absence of code is not penalized when the guidance is this actionable; this matches anchor 5's 'copy-paste ready commands; specific examples cover the common cases'.

Workflow Clarity

"Diff Analysis Order" is a clearly sequenced 4-step procedure with explicit ordering constraints ("Do not start by judging copied example files in isolation", "Only then inspect copied example files"), and "Synchronizing Copies" provides a full feedback loop: the "--set-exit-if-changed" generate-internal diff gate detects copy drift, then fix the source-of-truth template first, run sync-cargokit-copies, and commit. This matches anchor 5's 'clear sequence with explicit validation steps; feedback loops for error recovery'; anchor 4 would leave validation implicit, which it is not.

Progressive Disclosure

This is a compact single-file skill with no bundle files present and no content that clearly belongs in separate references — the ~85 lines of domain knowledge sit appropriately inline. Sections are well-organized and discoverable, and the Scope Boundary cleanly delegates to sibling skills ("Use `frb-code-generation`...", "Use `frb-debugging`...") rather than inlining their material. Per the rubric's simple-skill guidance, this matches anchor 5; there are no buried or nested references that would pull it down.

Specificity

The description lists several concrete actions — "Explain how cargokit is sourced, copied, and analyzed" and "identify the true source of truth before judging the change" — which matches anchor 4's 'several specific actions; minor gaps'. It falls short of anchor 5 because the actions are framed at a high level ('Explain', 'identify') rather than the comprehensive concrete action list of a 5, and well above anchor 3, which expects only 1-2 concrete actions without the multi-trigger purpose clause.

Completeness

Both halves are explicit: the 'what' is "Explain how cargokit is sourced, copied, and analyzed inside flutter_rust_bridge" and the 'when' is a concrete "Use when working on... or any diff that mentions cargokit" clause with multiple specific triggers. This matches anchor 5 ('clearly and explicitly answers both what AND when with concrete trigger phrases') exactly; anchor 4 would require the 'when' to be less explicit or specific, which it is not.

Trigger Term Quality

It has good natural keyword coverage: "any diff that mentions cargokit", "integration_template/**/cargokit", "frb_example/**/cargokit", and "integrate/generate output drift" are phrases a user in this repo would naturally say. Anchor 5 requires comprehensive synonym coverage, and a few natural terms are missing — notably "submodule" (the most common way users describe this change) and the "FRB" abbreviation — so it fits anchor 4 better than 5, and clearly better than anchor 3's 'missing common variations'.

Distinctiveness Conflict Risk

It carves out a clear niche — cargokit ownership and propagation inside flutter_rust_bridge — with path-specific triggers (`integration_template/**/cargokit`, `frb_example/**/cargokit`) that virtually no other skill would claim. This matches anchor 5's 'clear niche with distinct triggers; minimal conflict risk'; there is no meaningful overlap risk with generic skills.