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 MartinOlivero/saas-builder --skill paymentsgit clone --depth 1 https://github.com/MartinOlivero/saas-builderWrote 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/martinolivero/saas-builder/payments)<a href="https://agentmods.dev/skills/martinolivero/saas-builder/payments"><img src="https://agentmods.dev/badge/skills/martinolivero/saas-builder/payments/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/martinolivero/saas-builder/payments"><img src="https://agentmods.dev/badge/skills/martinolivero/saas-builder/payments.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 | $0.00110 | $0.01214 |
| Opus 5 | $0.00055 | $0.00607 |
| Sonnet 5 | $0.00022 | $0.00243 |
| Haiku 4.5 | $0.00011 | $0.00121 |
Grade A, and why
payments 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 10d 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.
How it starts
The opening of the file, as written. The whole thing — 71 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Payments
This skill turns an app into a SaaS that actually collects money — and does it without the classic bugs (fulfilling on the client redirect, double-granting access, unverified webhooks).
Analogy: the checkout redirect is the customer saying "I'll pay." The webhook is the bank confirming the money arrived. You ship the product when the bank confirms, not when the customer promises. Trusting the redirect is shipping on a promise.
The Stripe MCP split (read this first)
A Stripe MCP may be available (mcp__stripe__*). It is control-plane only: it creates products, prices, and payment links, and reads/updates subscriptions and customers. It cannot create Checkout Sessions or process webhooks.
So the architecture is hybrid:
- Delegate the catalog to the MCP — use it to create products, prices, and one-off payment links (the lowest-effort path for an MVP).
- Embed the integration code — Checkout Session creation, the webhook handler, and fulfillment must live in your shipped code, because the MCP can't do them.
If no MCP is present, create the catalog by hand in the Stripe dashboard or via the SDK; everything else below is identical.
Backend delegation: if you're on InsForge (see the data-modeling skill), its insforge / insforge-cli skills wire Stripe checkout, subscriptions, the customer portal, and the webhook handler for you — let them own the plumbing. The rules below still hold regardless (fulfill only on the webhook, verify the signature, stay idempotent); InsForge automates the wiring, it doesn't change what "correct" means. On Vercel/Node you write the handler yourself as shown. Never block on a missing skill.
Discovery (max 3 questions, only if unknown)
- One-time payments, subscriptions, or both?
- Do you want the fastest path (hosted Checkout) or a fully custom in-page card form (Elements)?
- What's the backend for the webhook — Vercel functions, a Node server, or a BaaS?
Step 1 — Pick the integration
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.
- 10d ago First seen · 71 lines · 110 tokens per session scan A 1f2b6c2c427d
payments is a skill published in the GitHub repository MartinOlivero/saas-builder (2 stars, last pushed 22d ago), licensed MIT. It adds 110 tokens to every session and 1,214 once invoked, about $0.0006 per session on Opus 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 2026-08-31.
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