credit-card-luhn SKILL.md skillA
credit-card-luhn from nebutra/nebutra-sailor is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add nebutra/nebutra-sailor/credit-card-luhn@v1.0.0Pins v1.0.0 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- nebutra/nebutra-sailor
- Path
packages/ai/forge-runtime/skills/credit-card-luhn/SKILL.md- Versions recorded
- 1
- Latest version
- v1.0.0, committed Aug 27, 2026
- Size
- 957 bytes
- Repository stars
- 5
- License
- Apache-2.0
Luhn algorithm check for card numbers (offline, never stored).
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
## What this skill does
Luhn algorithm check for card numbers (offline, never stored)
中文：Luhn 算法校验卡号格式（不联网、不存储）
## When to use
- Human or agent needs **Credit Card Luhn Checker** (`finance/credit-card-luhn`).
- Tier: `core` · side-effect: `pure` · meter: `forge.finance.credit_card_luhn`.
## How to invoke
```http
POST /api/v1/tools/invoke/finance/credit-card-luhn
Content-Type: application/json
{"input":{}}
```
MCP name: `finance__credit-card-luhn`
## Engine
- **luhn** 0.1.0
- Upstream: ISO/IEC 7812 Luhn algorithm
## Composition (next)
Chain these after a successful run when the job continues:
- (none seeded yet)
## Limits
- Prefer pure/deterministic path; do not invent model calls.
- Respect input schema validation errors from invoke.Read the whole file at its exact version.
How to install
mdr add nebutra/nebutra-sailor/credit-card-luhn@sha256:5fd2ab09b8b62eedThe line at the top of this page pins the label v1.0.0, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_h6oebbaltgazfzew)
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Versions
The registry has recorded 1 version of this file, committed on Aug 27, 2026.
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (957 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
nebutra/nebutra-sailor · 5 stars · license Apache-2.0 · pushed 2026-10-22 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_h6oebbaltgazfzew GET https://markdownregistry.com/api/v1/resolve?ref=nebutra/nebutra-sailor/credit-card-luhn GET https://markdownregistry.com/api/v1/blob/5fd2ab09b8b62eed84cebaa7125b4ec139141f9ef34712d1870ceddd48fb0a95
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.