Conciseness

The ~70-line body is dense with repo-specific policy ("all pinned exactly to 4.0.3 — never ^", "ESLint bans them in ts/packages/cli/src", "V4 does not generate a layer for you") and defers detail to references ("See '"Effect.gen' vs 'Effect.fn' in core-patterns"). Nothing explains general concepts Claude already knows; the one long bullet about Effect.fn is per-clause actionable guidance, not padding.

Actionability

Concrete, copy-paste commands are given ("pnpm typecheck", "pnpm --filter @composio/cli test", "node .agents/skills/effect-v4/scripts/check-examples.mjs") and every pattern names exact APIs ("Layer.succeed/Layer.effect/Layer.provide", "Effect.catchTag/catchTags/Match", "Effect.tryPromise({ try, catch })"). It falls short of anchor 5 only because no complete inline code example covers the common case (defining a Context.Service) — code excerpts are delegated to the references.

Workflow Clarity

Validation checkpoints are explicit (typecheck, filtered test run, skill validators, example compilation) with a stated gate ("the compiler is the compatibility gate") and a feedback loop ("when it and a reference disagree, trust the file and fix the reference"). Not anchor 5 because the body presents verification as a command block without an ordered sequence, and the main multi-step procedure (the upgrade workflow) lives in a reference rather than being sequenced here; not anchor 3 because checkpoints are present and explicit.

Progressive Disclosure

Clean overview/hub structure: three clearly signaled one-level-deep references with content summaries (all three exist in references/), scripts/check-examples.mjs present, and details appropriately split out of the body. One real gap against the actual bundle: "See [versions.json](versions.json) for the full matrix" points to a file that is absent from the skill directory, and typescript-testing/references/effect-v4-cli.md is a cross-skill path unverifiable from this bundle — minor navigation gaps that keep this below anchor 5.

Specificity

"Write, review, or upgrade Effect v4 code in the Composio CLI, cli-keyring, and json-schema-to-effect-schema packages" names multiple concrete actions (write, review, upgrade, answer API questions, bump pins, verify against the vendored oracle) and grounds each in specific surfaces: "Context.Service and explicit layers, Schema.TaggedError and typed recovery, the effect/cli command surface". Coverage is comprehensive, matching the anchor-5 example's breadth rather than the 'minor gaps' of anchor 4.

Completeness

Both halves are explicit: the 'what' opens the description ("Write, review, or upgrade Effect v4 code... all pinned exactly to effect@4.0.3") and the 'when' is a full "Use when..." clause with concrete trigger phrases. This is a direct structural match to the anchor-5 exemplar, not merely the adequate-but-looser anchor-4 form.

Trigger Term Quality

The trigger vocabulary is exactly what a developer in this repo would say: "Effect v4 code", "v4 API question", "working in effect/cli", "defining a Context.Service service", "modeling an error with Schema.TaggedError", "bumping the Effect pins", "verifying an unfamiliar API against ts/vendor/effect". For this domain the API names are the natural user terms, and the list spans seven distinct trigger scenarios with synonyms (write/review, pinned/version language).

Distinctiveness Conflict Risk

The niche is tightly scoped (Effect v4 in three named packages at an exact pin), and it adds explicit negative routing: "Do not use for CLI command UX/wiring design (use cli-command) or CLI E2E tests (use cli-e2e)". That boundary guidance actively steers adjacent queries to sibling skills, minimizing conflict risk beyond even the anchor-5 exemplar.