Clash of Coins
Agentic checkout for Clash of Coins
For Humans
If you are a human: give your agent this skill and this service link.
- Skill: https://x402.clashofcoins.com/skill.md
- Service URL: https://x402.clashofcoins.com
- Suggested prompt: “Install or read this skill, then use this Clash of Coins API to discover offers and complete the purchase flow.”
Unified discovery
- OpenAPI
- MCP manifest
- Aggregated catalog
- Aggregated resources
- Agent card
- Agents document
- llms.txt
- skill.md
- robots.txt and sitemap.xml
- pricing
- pricing.md
- Use case: agentic checkout for gaming platforms
- about, contact, privacy
- compare and alternatives
- Claude, Cursor, VS Code, Goose, Windsurf
- Published universal skill
- Published skills index
- Well-known skills index alias
- AgentCash validator skill
Use case: agentic checkout for gaming platforms
x402.clashofcoins.com is a production use case of agentic checkout for gaming platforms: agents can discover game offers, quote purchases, complete payment-challenge retries, and verify final delivery status.
What agents can do
Agents can discover the active catalog, compare sale and shop items, quote the exact payable request, receive a 402 PAYMENT-REQUIRED challenge, retry with the payment header, and poll delivery or ledger status before creating another payment.
Why x402 for game checkout
x402 keeps payment authorization attached to the HTTP request that creates the purchase. That makes the unpaid challenge, paid retry, settlement receipt, and delivery state visible to autonomous agents without hiding them behind card-session state.
Reliability and settlement model
Payment settlement is not treated as final game fulfillment by itself. The gateway persists purchase state, records payment references, calls the game delivery API for shop items, and exposes status routes for recovery.
How duplicate payments are avoided
Agents should preserve request bodies and idempotency keys, inspect existing payment references, and poll status routes after timeouts or 5xx responses before sending another mutating purchase request.
What makes this different
This is an alternative to generic PSP checkout for agentic game commerce: catalog, MCP tools, OpenAPI, OAuth metadata, x402 challenge semantics, recipient routing, and fulfillment recovery are all published on-domain for scanners and agents.
MCP and Skills
npm run mcp:gatewayGATEWAY_MCP_BASE_URL=https://x402.clashofcoins.com- /.well-known/mcp and server-card.json
- /.well-known/api-catalog
- OAuth authorization server metadata
- OAuth protected-resource metadata
- HTTP message signatures directory
- Repository configs:
.claude/mcp.json,.cursor/mcp.json,.windsurf/mcp_config.json. - Repository rules:
CLAUDE.md,.cursorrules,.windsurfrules. - Stable universal skill aliases:
/skills/SKILL.md, /skills/clashofcoins-universal/skill.md, /skills/clashofcoins-universal, /skills/clashofcoins/SKILL.md, /skills/clashofcoins/skill.md, /skills/clashofcoins - Universal skill bundle:
/skills/clashofcoins-universal/agents/openai.yaml, /skills/clashofcoins-universal/references/, /skills/clashofcoins-universal/scripts/, /skills/clashofcoins-universal/evals/ - The published skills catalog is exposed at /skills/index.json.
Presale checkout
POST /agentic/x402/buy
- x402 buy —
/agentic/x402/buy - saleId 391 — 9 USDC
- saleId 392 — 90 USDC
- saleId 393 — 900 USDC
- saleId 394 — 270 USDC
Game shop checkout
https://x402.clashofcoins.com/shop
- Recipient-scoped checkout — use the shop surface under
/shop. - x402 offers —
/shop/x402/offers - x402 quote —
/shop/x402/quote - x402 buy —
/shop/x402/buy - x402 status —
/shop/x402/purchases/{paymentReference}