Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add PostOakLabs/ainumbers --skill ap2-cart-to-payment-chaingit clone --depth 1 https://github.com/PostOakLabs/ainumbersWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/postoaklabs/ainumbers/ap2-cart-to-payment-chain)<a href="https://agentmods.dev/skills/postoaklabs/ainumbers/ap2-cart-to-payment-chain"><img src="https://agentmods.dev/badge/skills/postoaklabs/ainumbers/ap2-cart-to-payment-chain/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/postoaklabs/ainumbers/ap2-cart-to-payment-chain"><img src="https://agentmods.dev/badge/skills/postoaklabs/ainumbers/ap2-cart-to-payment-chain.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00051 | $0.00585 |
| Opus 5.5 | $0.00020 | $0.00234 |
| Sonnet 5.5 | $0.00010 | $0.00117 |
| Haiku 4.5 | $0.00005 | $0.00059 |
Grade A, and why
ap2-cart-to-payment-chain scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 15d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
What it actually says
AP2 cart to payment chain
Build an AP2 mandate, validate it, hash-chain the cart, and correlate it with an x402 settlement.
Prompt
Walk one synthetic purchase through the full AP2 evidence chain.
- Call draft_ap2_mandate_credential for a synthetic cart (two line items, a spend cap, an expiry). Record the credential id.
- Call validate_ap2_mandate_credential on the draft. Confirm the signature structure and the cap/expiry fields; record pass/fail.
- Tamper-test: change one line item's price in the signed cart, re-validate, and confirm the validator rejects it. Revert.
- Call build_ap2_cartmandate_hashchain over the cart events. Record the chain root.
- Call validate_ap2_mandate_chain on the chain. Record pass/fail and which links are covered.
- Call simulate_x402_flow for the settlement, then correlate_ap2_cartmandate_x402 to bind the settlement to the mandate chain. Record the correlation verdict.
- build_session_receipt over every hash; give me the ledger link.
- Write the note for the payments team: which claims the chain proves (mandate integrity, cart binding, settlement correlation), what it does not prove (merchant delivery), and the ledger link. Call shape: every ChainGraph node tool takes its arguments nested under one wrapper object, e.g. {"policy_parameters": { ... }}; flat arguments are discarded by schema validation. If a named tool is not in your tool list, call call_tool with { "name": "", "arguments": { … } }. It runs the same validation and returns the same receipt.
How to run
Connect an MCP-capable host to https://mcp.ainumbers.co/mcp, then give the prompt above to the assistant.
Use synthetic inputs only. Never paste personal or production data.
Verify what came back
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 15d ago Changed 56cd81595ffb
- 19d ago First seen · 41 lines · 51 tokens per session scan A 5d648d64a23d
ap2-cart-to-payment-chain is a skill published in the GitHub repository PostOakLabs/ainumbers (11 stars, last pushed yesterday), licensed MIT. It adds 51 tokens to every session and 585 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-27.
Other skills, from other repositories
starknet-tongo
Confidential ERC20 payments on Starknet using Tongo protocol. Fund, transfer, withdraw, and rollover encrypted token balances with zero-knowledge proofs. Use when the user needs privacy-preserving transactions, confidential payments, encrypted balances, or auditable private transfers on Starknet.
kb-crypto-adgm-sboghossian
Use when advising on virtual asset regulation in the Abu Dhabi Global Market (ADGM), including the FSRA Crypto Asset Regulatory Framework (in force since 2018 — the MENA region's first), ACASP licensing, Accepted Crypto Assets list, token issuance, custody requirements, AML obligations, stablecoin regime, and…
kb-crypto-vara-dubai-sboghossian
Use when advising on virtual asset regulation in Dubai under VARA (Virtual Assets Regulatory Authority), including license categories (advisory, brokerage, custody, exchange, lending, payments, issuance), the Rulebook suite (Company, Compliance and Risk, Technology, Market Conduct, Marketing, Virtual Asset Activities…
fintech-expert
Expert in financial technology, payment processing, open banking APIs, PSD2, blockchain in finance, robo-advisors, and RegTech. Use when the user mentions payments, open banking, PSD2, blockchain, cryptocurrency, or robo advisor, or when the task involves Payment Processing, Blockchain in Finance, Payment Security, or…
risk-assessment
Deterministic heuristic risk scoring using a four-factor weighted model (Geographic 30%, Customer 35%, Product 25%, Channel 10%) aligned with Basel III, EBA Guidelines, FATF standards, and FinCEN guidance. Bands: LOW (0-20), MEDIUM (21-60), HIGH (61-80), CRITICAL (81-100).
CronusCapital
Cronus is an autonomous, self-sustaining market-intelligence agent on the Arc network. It reasons over live market data with a real LLM, sells its signals via x402, spends on upstream data, settles on-chain in native USDC, and reports its own P&L - all non-custodially (it never holds your private key).