Conciseness

The prose does not pad with concepts Claude already knows — the content is dense, non-obvious domain knowledge ("the exact-SVM scheme makes the facilitator the transaction fee payer", "verification does not consume the authorization (settlement does)"). But the body runs ~585 lines with extended digressions (a ~140-line buyer client, a ~150-line Redis replay-protection server, Solana ATA provisioning) that exceed a lean SKILL.md, fitting the 3 anchor ('mostly efficient but could be tightened') rather than 2, since the length is information-rich rather than padded.

Actionability

Guidance is fully executable and copy-paste ready: pinned commands ("npm install -g agentwallet-sdk@6.0.0"), complete MCP JSON config, runnable TypeScript with pinned versions ("@x402/fetch@2.22.0"), a curl + jq account-existence check, and exact package/URL references per runtime. This matches the 5 anchor; the single declared stub ("declare function confirmWithUser") is explicitly justified ("Supply this from your harness — a real prompt, never a stub").

Workflow Clarity

A decision tree routes each need to a concrete path, and each path carries numbered steps with explicit validation checkpoints and error recovery: "Always verify success — a silent failure means no controls are active", the five-path fail-closed preToolCheck, "Test the policy adversarially — feed it a challenge demanding 5000000 atomic units… and assert that none of them produce a signature", and "Confirm live coverage at the facilitator's /supported endpoint before production". This matches the 5 anchor (clear sequence, explicit validation, feedback loops).

Progressive Disclosure

No references/, scripts/, or assets/ files exist — everything lives in one monolithic 585-line SKILL.md. Content that clearly belongs in separate files is inlined (facilitator comparison, Solana ATA provisioning guide, the full seller-side replay-protection implementation), which matches the 2 anchor despite the good section headers; it does not reach 3 because that anchor requires references to be present (even unclearly signaled), and here there are none.

Specificity

"Add x402 payment execution to AI agents with per-task budgets, spending controls, and non-custodial wallets" lists multiple concrete capabilities, and the description further names concrete integration actions ("Supports Base through agentwallet-sdk, X Layer through OKX Payments / OKX Agent Payments Protocol, and Solana plus multi-network EVM through the upstream x402 packages with facilitator-based settlement"). This matches the 5 anchor (multiple specific concrete actions, comprehensive) rather than 4, since coverage spans actions, networks, and settlement mechanics with no significant gaps.

Completeness

Both parts are explicit: what — "Add x402 payment execution to AI agents with per-task budgets, spending controls, and non-custodial wallets"; when — "Use when an agent must pay for something itself and needs per-task budgets, spending controls, and a non-custodial wallet." The 'Use when' clause contains concrete trigger phrases, matching the 5 anchor exactly; it does not fall to 4 because the 'when' is explicit and specific rather than vague.

Trigger Term Quality

Natural phrases are present ("agent must pay for something itself", "per-task budgets", "spending controls", "non-custodial wallet", named chains Base/X Layer/Solana), which is good keyword coverage. A few natural terms a user would say are missing (e.g., "agent wallet", "micropayments", "agent paying for API calls", "spending limits"), so it fits the 4 anchor rather than 5's comprehensive synonym coverage; it is well above 3's 'missing common variations'.

Distinctiveness Conflict Risk

The description occupies a clear niche (x402 protocol, agentwallet-sdk, OKX Payments, facilitator-based settlement) with distinct triggers ("agent must pay for something itself"), so it is unlikely to fire for unrelated skills. It matches the 5 anchor (clear niche, distinct triggers, minimal conflict risk) rather than 4, which reserves for overlap with closely related skills.