Conciseness

The body is dense and expert-level — it assumes knowledge of HMAC, webhooks, and Node crypto, and never explains background concepts — but a few sections pad the token budget: the 13-item Related Skills list, the Attribution section, and the disambiguation note repeated verbatim from the description. These are minor trims, matching the "efficient; minor instances of over-explanation" anchor rather than the lean 5.

Actionability

The core verification code is complete, copy-paste ready, and fail-closed (length guard before timingSafeEqual, missing-header check), with a real example key value, exact retry schedule (8 attempts with intervals), a runnable local-dev command (`npx hookdeck-cli listen 3000 ...`), and an explicit "verify, enqueue, return 2xx" guidance line. This matches the fully-executable anchor covering the common cases.

Workflow Clarity

The handler sequence is clearly laid out (set signature key → verify raw-body HMAC → optionally check Authorization → dedupe on evt id → ack within 10s) with validation behavior embedded in the code (fail closed, length guard) and explicit error consequences ("uncaught throw becomes a 500, which Checkout.com retries eight times"). It falls short of the 5 anchor because there is no explicit ordered checklist or debug-on-failure loop in the body itself — recovery guidance is delegated to references/verification.md.

Progressive Disclosure

Structure is good: three one-level-deep reference files (overview.md, setup.md, verification.md) are well-signaled with per-file content summaries, and all three exist in the bundle with matching content. The gap against the 5 anchor is the "For complete handlers with tests, see examples/express/, examples/nextjs/, examples/fastapi/" pointers — no examples/ directory exists in the bundle, so those references are broken.

Specificity

Concrete actions are explicitly named — "Receive and verify Checkout.com webhooks", "debugging Cko-Signature verification", "handling events like payment_approved, payment_captured, payment_declined, payment_refunded, dispute_received or fraud_reported" — plus the exact verification mechanism ("HMAC-SHA256 over the RAW body, hex-encoded, in the Cko-Signature header"). Coverage is comprehensive, matching the anchor for multiple specific concrete actions; nothing is vague or generic.

Completeness

The description answers "what" explicitly ("Receive and verify Checkout.com webhooks ... signs with HMAC-SHA256 over the RAW body, hex-encoded ... optionally send a static Authorization header key") and "when" with a concrete "Use when" clause listing three trigger scenarios. This matches the anchor that clearly and explicitly answers both what AND when with concrete trigger phrases.

Trigger Term Quality

Natural user phrasing is thoroughly covered: "setting up a Checkout.com webhook handler", "webhook handler", "Cko-Signature verification", "payment_approved / payment_captured / payment_refunded / dispute_received" — the exact event names and header names a user would type. Domain URL (checkout.com) and command-style phrases are present; no common synonyms missing.

Distinctiveness Conflict Risk

It hardens the niche with explicit exclusions — "Not Checkout Page (checkoutpage.com), not CheckoutJoy, not 2Checkout / Verifone, not Stripe Checkout, not Shopify checkout webhooks" — alongside the exact provider identity and header/event vocabulary. Conflict risk with similarly-named skills is minimal, matching the clear-niche anchor.