Conciseness

The body is efficient and avoids tutorial padding: a compact six-step flow diagram, short focused code blocks, and a security checklist with no filler. Minor instances of over-explanation remain (e.g., '# Subject (unique user ID)' and '# ID token contains user identity claims' restate concepts Claude already knows), keeping it just below the lean anchor of 5 and above anchor 3's 'some unnecessary explanation'.

Actionability

Guidance is partially concrete but incomplete: the PKCE snippet uses non-executable pseudocode ('base64url(sha256(code_verifier))'), 'refresh_tokens' is a stub ending in 'pass', and the flow section describes steps rather than giving runnable code. This matches the anchor for 'some concrete guidance but incomplete; pseudocode instead of executable code; missing key details' — it is above anchor 2 because real parameter names, code_challenge_method, and claim structures are given.

Workflow Clarity

The authorization code flow is presented as a clear numbered sequence, and the checklist mentions validation concerns ('Validate state parameter against CSRF', 'Verify ID token signature'), but the two are not integrated into a sequenced workflow: there are no explicit checkpoints at step boundaries and no feedback/recovery loop for token or validation failures. This matches anchor 3 ('steps listed but validation gaps; sequence present but checkpoints missing or implicit') rather than 4, where most checkpoints would be embedded in the sequence.

Progressive Disclosure

The single-file body is well organized into clear sections (Flows, Token Management, Security, OIDC, Checklist), and nothing here clearly belongs in a separate reference file, so it does not suffer the inlining penalty of anchors 2-3. It falls just short of anchor 5 because the body runs well past the ~50-line simple-skill threshold and is entirely monolithic — e.g., the OIDC claims detail could live in a one-level-deep reference — so 'good structure, minor organization gaps' at 4 is the best fit.

Specificity

The description names the domain clearly ('OAuth 2.0 and OpenID Connect implementation patterns') with actions like 'implementing authentication, authorization flows, or integrating with OAuth providers', but these are 1-2 generic actions rather than a list of specific concrete capabilities. It sits at the anchor for naming the domain with a couple of concrete actions but not comprehensive coverage; it is above anchor 2 because the actions are more concrete than merely naming the domain.

Completeness

It has an explicit 'Use when...' trigger clause ('Use when implementing authentication, authorization flows, or integrating with OAuth providers like Google, GitHub, or custom identity providers') and a 'what' ('OAuth 2.0 and OpenID Connect implementation patterns'). The 'when' is explicit and specific, but the 'what' is somewhat thin — 'implementation patterns' is vaguer than listing concrete operations — so it matches anchor 4 rather than the fully concrete what-and-when of anchor 5.

Trigger Term Quality

Good natural keyword coverage: 'authentication', 'authorization flows', 'integrating with OAuth providers', 'Google, GitHub, or custom identity providers'. A few natural terms users would say are missing (e.g., 'login', 'sign in', 'SSO', 'tokens', 'OIDC'), so it does not reach the comprehensive-with-synonyms anchor of 5, but it clearly exceeds 'some relevant keywords with missing variations' at 3.

Distinctiveness Conflict Risk

It carves out a clear niche (OAuth 2.0 / OIDC implementation) with distinct trigger phrases naming specific providers, and would not plausibly fire for unrelated skills. This matches the 'clear niche with distinct triggers; minimal conflict risk' anchor.