Universal Checkout Skill

Zinc Skills: Universal Checkout for AI Agents

Agent Skills for buying products and managing orders through the Zinc API — programmatic checkout across Amazon, Walmart, Target, Best Buy, eBay, and 50+ other retailers with a single API.

This repo ships the universal-checkout skill (every retailer, full order lifecycle) plus per-retailer skills for the retailers people search for by name. Install the universal one for general use; install a retailer-specific one when you only buy from a single store.

Skills

Which should I install? The per-retailer skills are the same full lifecycle (order → track → manage) retargeted for one store — handy when an agent only ever buys from, say, Amazon, and for discovery. If you buy across multiple retailers, install universal-checkout instead of stacking several near-identical retailer skills (overlapping descriptions can make skill triggering ambiguous).

Live supported-retailer list: GET https://api.zinc.com/retailers.

Task skills

Hand-maintained skills for a specific task rather than a retailer. They place orders through the Zinc API and pay per order with a Stripe Link card via the create-payment-credential skill — no Zinc API key needed.

What these skills do

Full US shopping lifecycle — discover → buy → track → return:

• Discover — GET /search (cross-retailer, returns orderable URLs; filter with a repeatable retailer, which also takes etsy and up to 3 Shopify stores, searched only when named; an Etsy listing with options needs a variant on the order, listed by GET /products/{id}?retailer=etsy; Amazon, Walmart, Etsy and Shopify results carry a product_id — pass it with the result's retailer to GET /products/{id}, or /offers on Amazon and Walmart, to check the live price before ordering — live details and offers); GET /products/search + GET /products/{id} / GET /products/{id}/offers for best-price comparison on one retailer (Amazon and its other marketplaces, Walmart, Best Buy, Etsy, and Shopify stores — which retailer to pass). A Shopify store Zinc hasn't catalogued yet is checked and added on a live key's first request for it by domain (pass retailer=<store domain>); test keys and the MPP rail only reach stores already in the catalog. On the MPP rail (no account), the same data is available via the metered /agent/* endpoints at $0.01/call; GET /retailers is free.
• Place orders — POST /orders (API key) or POST /agent/orders (Machine Payments Protocol — pay per request via Stripe cards/wallets or Tempo stablecoins, no account needed), with condition filters, handling_days_max, variants, and is_gift
• Track & manage — GET /orders, GET /orders/{id} (tracking + price breakdown), POST /orders/{id}/cancel
• Returns — POST /returns, GET /returns
• Error handling — full code reference in each skill's references/errors.md

Prerequisites

• API Key auth: A Zinc API key (sign up at app.zinc.com). Set ZINC_API_KEY.
• MPP auth: No Zinc account needed — pay per request via Tempo stablecoins (set TEMPO_PRIVATE_KEY) or Stripe (cards/wallets via Stripe Link). Try it without code at agent.zinc.com.

Installation

These are Agent Skills — folders containing a SKILL.md with metadata and instructions that any compatible agent (Claude Code, Cursor, Gemini CLI, VS Code, GitHub Copilot, and many others) can discover and use.

# Universal skill (recommended for most users)
npx skills add zincio/skills --skill universal-checkout

# A single retailer
npx skills add zincio/skills --skill amazon-checkout

# List everything in this repo
npx skills add zincio/skills --list

Or clone and point your agent at the skills/ directory:

git clone https://github.com/zincio/skills.git

Skills use progressive disclosure — at startup only name and description load; full instructions are read into context only when a matching task is detected.

OpenClaw

OpenClaw loads skills from the workspace (<workspace>/skills/), user (~/.openclaw/skills/), and bundled locations. OpenClaw hot-reloads skills when SKILL.md changes — no restart needed.

Repo layout & maintenance

├── references/errors.md           # shared error reference (single source)
├── skills/
│   ├── universal-checkout/         # the universal skill — all retailers (hand-maintained)
│   │   ├── SKILL.md
│   │   └── references/errors.md
│   └── <retailer>-checkout/        # per-retailer skill (generated, self-contained)
│       ├── SKILL.md
│       └── references/errors.md
└── tools/
    ├── generate_skills.py         # generates every skills/<retailer>-checkout/ folder
    └── retailers.json             # committed snapshot of GET /retailers (the catalog)

The per-retailer skills — and the skills table above — are generated, not hand-edited. The retailer catalog (which retailers exist, display name, base URL, free-shipping terms) comes from the live GET https://api.zinc.com/retailers endpoint — the single source of truth — captured in tools/retailers.json. The only things not in the endpoint are an example product URL (derived from the domain) and which retailers have /products/search (one constant in the generator); retailer-specific order constraints aren't encoded — the order API reports them at request time.

python3 tools/generate