Borrowing it
Nothing to install: this file belongs to mrslbt/paypay-mcp. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/mrslbt/paypay-mcp/main/AGENTS.mdgit clone --depth 1 https://github.com/mrslbt/paypay-mcpWrote 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/instructions/mrslbt/paypay-mcp/agents-md)<a href="https://agentmods.dev/instructions/mrslbt/paypay-mcp/agents-md"><img src="https://agentmods.dev/badge/instructions/mrslbt/paypay-mcp/agents-md.svg" alt="Measured on agentmods" 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 | $0.02571 | $0.02571 |
| Opus 5 | $0.01286 | $0.01286 |
| Sonnet 5 | $0.00514 | $0.00514 |
| Haiku 4.5 | $0.00257 | $0.00257 |
Grade A, and why
paypay-mcp AGENTS.md 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 7d 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 — 211 lines — stays where its author put it; the contents beside it link to each section on GitHub.
AGENTS.md — paypay-mcp
Instructions for AI coding agents (Codex, Cursor, Copilot, Claude Code, etc.) contributing to this repository.
What this project is
paypay-mcp is a Model Context Protocol server for the PayPay Open Payment API (PayPay OPA) — Japan's largest QR-wallet payment platform. It lets MCP-capable clients (Claude Desktop, Claude Code, Cursor, Cline, etc.) create QR codes, check payment status, and (opt-in) issue refunds or cancel payments.
Distribution: published to npm as paypay-mcp. Local stdio transport by default; streamable HTTP transport opt-in via MCP_TRANSPORT=http.
Quick commands
npm install # install dependencies
npm run typecheck # tsc --noEmit, must pass before commit
npm run build # tsc → dist/
npm test # vitest run — must pass before commit
npm run dev # tsx watch src/index.ts (stdio)
npm run start # node dist/index.js (stdio)
npm run start:http # node dist/index.js with MCP_TRANSPORT=http
npm run smoke # tests/smoke.mjs — connects to a real PayPay sandbox
npm run test:e2e # tests/mcp_e2e.mjs — full MCP protocol round-trip
Pre-commit: npm run typecheck && npm test. Both must pass. Tests currently complete in <1s; collection is the slow part (~2.5 min) — this is a known TS-loading cost, not a test failure.
Architecture (the only mental model you need)
src/
├── index.ts # entry point — dispatches to transport
├── config.ts # loadConfig() — env-driven, fails fast on missing required vars
├── auth.ts # PayPay OPA HMAC signing (verified against paypayopa/paypayopa-sdk-node)
├── client.ts # PayPayClient — wraps fetch + sign + error handling
├── errors.ts # PayPayError — typed error surfacing
├── logger.ts # structured stderr logger
├── server.ts # buildServer(config) — wires tools/prompts/resources into McpServer
├── transports/
│ ├── stdio.ts # StdioServerTransport (default)
│ └── http.ts # StreamableHTTPServerTransport with bearer-token auth + CORS
├── tools/
│ ├── types.ts # ToolDefinition<TInput>, ToolResult, helpers
│ ├── index.ts # tool registry — controls what gets registered
│ └── *.ts # one file per tool
├── prompts/index.ts # prompt registry
└── resources/index.ts # resource registry
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.
- 7d ago First seen · 211 lines · 2,571 tokens per session scan A 5bb678215894
paypay-mcp AGENTS.md is an instructions file published in the GitHub repository mrslbt/paypay-mcp (0 stars, last pushed 26d ago), licensed MIT. It adds 2,571 tokens to every session, about $0.0129 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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