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 williamzujkowski/standards --skill api-securitygit clone --depth 1 https://github.com/williamzujkowski/standardsWrote 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/williamzujkowski/standards/api-security)<a href="https://agentmods.dev/skills/williamzujkowski/standards/api-security"><img src="https://agentmods.dev/badge/skills/williamzujkowski/standards/api-security/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/williamzujkowski/standards/api-security"><img src="https://agentmods.dev/badge/skills/williamzujkowski/standards/api-security.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 | $0.00154 | $0.03442 |
| Opus 5.5 | $0.00062 | $0.01377 |
| Sonnet 5.5 | $0.00031 | $0.00688 |
| Haiku 4.5 | $0.00015 | $0.00344 |
Grade A, and why
api-security 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 yesterday.
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 — 515 lines — stays where its author put it; the contents beside it link to each section on GitHub.
API Security
Level System: Each skill contains three progressive levels
- Level 1: Quick Reference (600-800 tokens) - Essential patterns and checklists
- Level 2: Implementation Guide (3000-4500 tokens) - Detailed practices and examples
- Level 3: Deep Dive - Additional resources and advanced topics
Level 1: Quick Reference
OWASP API Security Top 10 (2023)
- Broken Object Level Authorization (BOLA) - API fails to validate user access to objects
- Broken Authentication - Weak or missing authentication mechanisms
- Broken Object Property Level Authorization - Missing field-level access control
- Unrestricted Resource Consumption - No rate limiting or throttling
- Broken Function Level Authorization - Missing authorization checks on endpoints
- Unrestricted Access to Sensitive Business Flows - Automated abuse of legitimate workflows
- Server Side Request Forgery (SSRF) - API accepts URLs without validation
- Security Misconfiguration - Insecure default configs, verbose errors
- Improper Inventory Management - Undocumented/deprecated APIs in production
- Unsafe Consumption of APIs - Trusting third-party API data without validation
Essential Security Checklist
transport_security:
- [ ] TLS 1.2+ enforced on all endpoints
- [ ] HSTS headers configured
- [ ] Certificate pinning for mobile clients
authentication:
- [ ] API keys rotated regularly
- [ ] OAuth 2.0 with PKCE for public clients
- [ ] JWT tokens with short expiration (15-60 min)
- [ ] Refresh token rotation implemented
authorization:
- [ ] Object-level authorization on all resources
- [ ] Field-level authorization for sensitive data
- [ ] Role-based or attribute-based access control
input_validation:
- [ ] Schema validation on all inputs
- [ ] Content-Type verification
- [ ] Request size limits enforced
- [ ] SQL injection prevention (parameterized queries)
rate_limiting:
- [ ] Per-user rate limits (e.g., 100 req/min)
- [ ] Per-IP rate limits for unauthenticated endpoints
- [ ] Exponential backoff on failed auth attempts
- [ ] Resource-specific quotas
monitoring:
- [ ] Authentication failures logged
- [ ] Authorization failures alerted
- [ ] Anomalous patterns detected (sudden spikes)
- [ ] Security events centralized (SIEM)
cors_configuration:
- [ ] Allowlist specific origins (no wildcards in prod)
- [ ] Credentials flag set appropriately
- [ ] Preflight cache configured
api_versioning:
- [ ] Deprecated versions documented
- [ ] Sunset headers on old versions
- [ ] Security fixes backported to supported versions
What ships with it
7 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.
- yesterday First seen · 515 lines · 154 tokens per session scan A 261d3ce7f451
api-security is a skill published in the GitHub repository williamzujkowski/standards (18 stars, last pushed 1mo ago), licensed MIT. It adds 154 tokens to every session and 3,442 once invoked, about $0.0006 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 2026-09-29.
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