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 Ghosteken/agent-harness --skill api-security-best-practicesgit clone --depth 1 https://github.com/Ghosteken/agent-harnessWrote 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/ghosteken/agent-harness/api-security-best-practices)<a href="https://agentmods.dev/skills/ghosteken/agent-harness/api-security-best-practices"><img src="https://agentmods.dev/badge/skills/ghosteken/agent-harness/api-security-best-practices/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/ghosteken/agent-harness/api-security-best-practices"><img src="https://agentmods.dev/badge/skills/ghosteken/agent-harness/api-security-best-practices.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 | $0.00029 | $0.05955 |
| Opus 5.5 | $0.00012 | $0.02382 |
| Sonnet 5.5 | $0.00006 | $0.01191 |
| Haiku 4.5 | $0.00003 | $0.00596 |
Grade A, and why
api-security-best-practices 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 1mo 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.
This is a copy
94% identical to api-security-best-practices — 1,016 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 916 lines — stays where its author put it; the contents beside it link to each section on GitHub.
API Security Best Practices
Overview
Guide developers in building secure APIs by implementing authentication, authorization, input validation, rate limiting, and protection against common vulnerabilities. This skill covers security patterns for REST, GraphQL, and WebSocket APIs.
When to Use This Skill
- Use when designing new API endpoints
- Use when securing existing APIs
- Use when implementing authentication and authorization
- Use when protecting against API attacks (injection, DDoS, etc.)
- Use when conducting API security reviews
- Use when preparing for security audits
- Use when implementing rate limiting and throttling
- Use when handling sensitive data in APIs
How It Works
Step 1: Authentication & Authorization
I'll help you implement secure authentication:
- Choose authentication method (JWT, OAuth 2.0, API keys)
- Implement token-based authentication
- Set up role-based access control (RBAC)
- Secure session management
- Implement multi-factor authentication (MFA)
Step 2: Input Validation & Sanitization
Protect against injection attacks:
- Validate all input data
- Sanitize user inputs
- Use parameterized queries
- Implement request schema validation
- Prevent SQL injection, XSS, and command injection
Step 3: Rate Limiting & Throttling
Prevent abuse and DDoS attacks:
- Implement rate limiting per user/IP
- Set up API throttling
- Configure request quotas
- Handle rate limit errors gracefully
- Monitor for suspicious activity
Step 4: Data Protection
Secure sensitive data:
- Encrypt data in transit (HTTPS/TLS)
- Encrypt sensitive data at rest
- Implement proper error handling (no data leaks)
- Sanitize error messages
- Use secure headers
Step 5: API Security Testing
Verify security implementation:
- Test authentication and authorization
- Perform penetration testing
- Check for common vulnerabilities (OWASP API Top 10)
- Validate input handling
- Test rate limiting
Examples
Example 1: Implementing JWT Authentication
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.
- 1mo ago First seen · 916 lines · 29 tokens per session scan A 93902629949b
api-security-best-practices is a skill published in the GitHub repository Ghosteken/agent-harness (4 stars, last pushed yesterday), licensed MIT. It adds 29 tokens to every session and 5,955 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 94% identical to api-security-best-practices, differing in 1,016 lines, and is treated as a copy.
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