Conciseness

The body is lean and imperative and assumes competence ("Never write AI SDK code from memory"). Minor over-explanation remains: the memory-distrust warning is repeated across 'Do Not Trust Your Own Memory' and 'Choosing a Model' ('Never use model IDs from memory'), and the 'What the AI SDK Is' opening restates broadly known facts. Efficient with minor trim opportunities — anchor 4.

Actionability

Contains executable, copy-paste commands (curl for the model list, 'npm view ai version', concrete node_modules/ai/docs/ paths including monorepo variants). No TypeScript examples, but omitting them is the skill's explicit, justified strategy — code from memory would contradict its version-matched-docs rule. Anchor 4: mostly executable with minor gaps (e.g. no example of grepping the bundled docs).

Workflow Clarity

A clear sequence runs verify-install → read version-matched docs → implement → 'Run the project's type checker', with a feedback loop ('re-check the current docs and source when they occur') and an explicit installed-vs-latest version comparison. No destructive or batch operations, so no validation cap applies; it stops short of anchor 5's full validate→fix→retry checkpoints and checklists.

Progressive Disclosure

No bundle files exist; the body is well-sectioned and delegates all version-sensitive detail one level deep to the installed package's docs (node_modules/ai/docs/) and ai-sdk.dev URLs — an appropriate split for a fast-moving SDK. Above the under-50-line simple-skill carve-out, so anchor 4 ('good structure; most content appropriately placed; references mostly clear') fits best.

Specificity

Enumerates ten concrete feature areas ("chat interfaces, text generation, structured output, tool calling, agents, MCP integration, streaming, embeddings, reranking, image generation"), but the core action is the generic phrase "expert guidance" — capability domains rather than concrete actions. Matches anchor 4; not 5 because there are no concrete action verbs like the anchor's 'extract/fill/merge', and clearly above 3's '1-2 concrete actions'.

Completeness

Both parts are present: an explicit "Use when building AI-powered features — ..." trigger clause with concrete triggers, and a what-claim. However the what ("Vercel AI SDK expert guidance") is vague, so it sits at anchor 4 rather than 5's fully concrete what+when pairing; the explicit 'when' keeps it above the weaker anchors.

Trigger Term Quality

Natural phrases users would say are present ("chat interfaces", "tool calling", "streaming", "embeddings", "any LLM provider"), giving good keyword coverage. Falls short of anchor 5 because common variations users actually type — e.g. 'useChat', 'streamText', 'Vercel AI' — are absent from the description itself.

Distinctiveness Conflict Risk

Clear niche (Vercel AI SDK) with distinct triggers, but the trailing "or working with any LLM provider" broadens the trigger surface into overlap with general LLM/provider skills. Anchor 4 ('mostly distinct; minor overlap risk with closely related skills') is the best fit.