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 oborchers/fractional-cto --skill auth-and-api-keysgit clone --depth 1 https://github.com/oborchers/fractional-ctoWrote 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/oborchers/fractional-cto/auth-and-api-keys)<a href="https://agentmods.dev/skills/oborchers/fractional-cto/auth-and-api-keys"><img src="https://agentmods.dev/badge/skills/oborchers/fractional-cto/auth-and-api-keys/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/oborchers/fractional-cto/auth-and-api-keys"><img src="https://agentmods.dev/badge/skills/oborchers/fractional-cto/auth-and-api-keys.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 3 findings, up to high
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- high Privilege Escalation · line 35 Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
- high Privilege Escalation · line 150 Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
- high Privilege Escalation · line 122 Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
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 | $0.00082 | $0.02440 |
| Opus 5 | $0.00041 | $0.01220 |
| Sonnet 5 | $0.00016 | $0.00488 |
| Haiku 4.5 | $0.00008 | $0.00244 |
Grade A, and why
auth-and-api-keys 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 — 188 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Authentication Should Be Invisible Until It Isn't
Authentication is the first impression your API makes. Before a developer can create a resource, list a record, or trigger a webhook, they must authenticate. If this step is confusing, insecure, or poorly designed, nothing else matters. A leaked key with no prefix is invisible until it causes a production incident. A missing 401/403 distinction wastes hours of debugging. A rotation flow that requires downtime erodes trust.
Design authentication so developers never think about it -- until the moment they need to rotate a key, scope a permission, or integrate a third-party OAuth flow. Then make that moment effortless.
API Key Design: Prefixes Are Non-Negotiable
Every API key must carry a prefix that encodes its type, environment, and provider. Prefixes enable automated secret scanning (GitHub secret scanning, GitGuardian), make wrong-key errors self-diagnosable, and prevent accidental production usage.
Use this format: {type}_{environment}_{random_entropy}
sk_live_-- secret key, productionsk_test_-- secret key, test/sandboxpk_live_-- publishable key, production (safe for client-side)pk_test_-- publishable key, test/sandboxrk_live_-- restricted key, production (scoped permissions)
Never issue opaque hex strings like a1b2c3d4e5f6.... They cannot be identified by scanners, cannot be distinguished by environment, and force developers to contact support for basic misuse diagnosis.
Industry Prefix Reference
| Provider | Prefix | Purpose |
|---|---|---|
| Stripe | sk_live_, sk_test_ |
Secret keys by environment |
| Stripe | pk_live_, pk_test_ |
Publishable keys by environment |
| Stripe | rk_live_, whsec_ |
Restricted keys, webhook secrets |
| GitHub | ghp_, ghs_, gho_ |
Personal, app, and OAuth tokens |
| GitHub | github_pat_ |
Fine-grained personal access token |
| Twilio | SK |
API key SID |
| Slack | xoxb-, xoxp- |
Bot token, user token |
| AWS | AKIA |
Access key ID |
| Cloudflare | v1.0- |
API token |
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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 · 188 lines · 82 tokens per session scan A 3fecd4f21193
auth-and-api-keys is a skill published in the GitHub repository oborchers/fractional-cto (29 stars, last pushed 1mo ago), licensed MIT. It adds 82 tokens to every session and 2,440 once invoked, about $0.0004 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 2026-08-30.
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