Conciseness

The body is dominated by dense decision tables and shell commands ("ls "$SRC/packages/better-auth/src/plugins"", "rg "^export " "$SRC/packages/better-auth/src/index.ts"") with no explanation of concepts Claude already knows. However, the "Do Not Trust Internal Knowledge" list states the enumerate-before-writing rule twice (items 2 and 4: "Verify plugin names, adapter imports, and option shapes" / "Never invent plugin names, adapter import paths"), and the verify-against-source instruction recurs across the Finding Documentation, adapters, plugins, and databases sections — minor trimmable redundancy that fits the 4 anchor rather than the 5 anchor's "every token earns its place".

Actionability

Guidance is copy-paste ready throughout: install commands, source resolution ("SRC=$(ask src better-auth)"), complete server/client setup code blocks, an exact per-framework mount table ("toNextJsHandler(auth) at app/api/auth/[...all]/route.ts"), adapter signatures ("prismaAdapter(prisma, { provider })"), and "npx auth generate / migrate". The single placeholder ("database: /* DB adapter or Kysely dialect — see references/databases.md */") is a required project-specific choice backed by a concrete adapter table and reference file, so it is a deliberate pointer rather than a missing detail — matching the 5 anchor, not the 4 anchor's "minor gaps".

Workflow Clarity

A clear sequence is laid out: verify install in the lockfile → resolve the installed version with `ask` → verify names before generating code → "Run typecheck after changes to surface silent breakage early", plus an explicit error-recovery feedback loop ("grep references/common-errors.md for the failing symptom … If the symptom is not listed, resolve the source and grep the error string"). Explicit validation checkpoints plus a fix-and-retry loop match the 5 anchor; the operations are code-generation rather than destructive/batch, so no cap applies.

Progressive Disclosure

The body is an overview with decision tables, and all detail lives in four real bundle files verified on disk: references/adapters.md, references/plugins.md, references/databases.md, and references/common-errors.md. Every inline pointer is clearly signaled with scope notes ("Full wiring, cookie handling, and CORS gotchas per framework: references/adapters.md") and a terminal References section lists all four with one-line descriptions — one level deep, matching the 5 anchor exactly.

Specificity

Beyond the opening "Answer questions about better-auth and help build authentication features", the description enumerates concrete actions with named specifics: APIs ("betterAuth", "auth.api.*", "authClient.*"), seven framework adapters (Next.js, Nuxt, SvelteKit, Hono, Astro, Bun, Express), six plugins, and four DB adapters (Prisma, Drizzle, Kysely, Mongoose). This matches the 5 anchor's "multiple specific concrete actions; comprehensive coverage"; it exceeds the 4 anchor because coverage spans every major capability area with no noticeable gap.

Completeness

It explicitly answers "what" ("Answer questions about better-auth and help build authentication features" plus five enumerated capabilities) and "when" ("Use when developers: (1)…(5)" and a dedicated "Triggers on:" list with concrete trigger phrases). This mirrors the 5 anchor's exemplar verbatim in structure; the 4 anchor's "'when' could be more explicit" does not apply since triggers are enumerated twice.

Trigger Term Quality

The trigger list includes natural terms and synonyms users would say: "better-auth", "betterAuth", "authClient", "sign in flow", "social login", "magic link", "passkey", "organization plugin". However, common natural phrasings such as "login", "sign up", "two-factor"/"2FA", and "authentication" are absent, which fits the 4 anchor ("good keyword coverage; a few natural terms missing") better than the 5 anchor's comprehensive synonym coverage.

Distinctiveness Conflict Risk

The niche is clear — every capability example names better-auth-specific symbols and the library name appears in two spellings among the triggers. But library-agnostic trigger phrases like "social login", "auth session", and "sign in flow" could fire for generic auth work or other auth libraries, fitting the 4 anchor ("mostly distinct; minor overlap risk with closely related skills") rather than the 5 anchor's "minimal conflict risk".