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 agentmods add skills/d-padmanabhan/agent-engineering-handbook/security-testingnpx skills add d-padmanabhan/agent-engineering-handbook --skill security-testinggit clone --depth 1 https://github.com/d-padmanabhan/agent-engineering-handbookWrote 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/d-padmanabhan/agent-engineering-handbook/security-testing)<a href="https://agentmods.dev/skills/d-padmanabhan/agent-engineering-handbook/security-testing"><img src="https://agentmods.dev/badge/skills/d-padmanabhan/agent-engineering-handbook/security-testing.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 | $0.00066 | $0.00976 |
| Opus 5 | $0.00033 | $0.00488 |
| Sonnet 5 | $0.00013 | $0.00195 |
| Haiku 4.5 | $0.00007 | $0.00098 |
Grade A, and why
security-testing 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 2d 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.
Copies of this mod
1 near-identical copy found in the catalogue:
- security-testing — 91% identical, 267 lines differ
How it starts
The opening of the file, as written. The whole thing — 135 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Security & Testing
Security Principles
- Defense in Depth: Multiple layers of security
- Least Privilege: Minimum necessary permissions
- Fail Secure: Default to deny
- Zero Trust: Never trust, always verify
OWASP Top 10 Quick Reference
| # | Vulnerability | Prevention |
|---|---|---|
| 1 | Broken Access Control | RBAC, deny by default, audit logs |
| 2 | Cryptographic Failures | TLS, strong algorithms, key management |
| 3 | Injection | Parameterized queries, input validation |
| 4 | Insecure Design | Threat modeling, secure patterns |
| 5 | Security Misconfiguration | Hardened defaults, minimal services |
| 6 | Vulnerable Components | Dependency scanning, updates |
| 7 | Auth/Identity Failures | MFA, session management |
| 8 | Software/Data Integrity | Signed artifacts, CI/CD security |
| 9 | Logging/Monitoring Failures | Centralized logs, alerting |
| 10 | SSRF | Input validation, allowlists |
Security Checklist
- No hardcoded secrets
- Secrets not logged
- Input validation on all boundaries
- Parameterized queries
- Dependencies scanned for CVEs
- Authentication & authorization implemented
- HTTPS enforced
- Security headers configured
- Rate limiting in place
- Audit logging enabled
Testing Pyramid
/\
/ \ E2E Tests (few)
/----\
/ \ Integration Tests
/--------\
/ \ Unit Tests (many)
/------------\
| Type | Purpose | Speed | Coverage |
|---|---|---|---|
| Unit | Test isolated logic | Fast | High |
| Integration | Test component interaction | Medium | Medium |
| E2E | Test full user flows | Slow | Low |
Testing Best Practices
# Arrange-Act-Assert pattern
def test_user_creation():
# Arrange
user_data = {"name": "Alice", "email": "[email protected]"}
# Act
user = create_user(user_data)
# Assert
assert user.name == "Alice"
assert user.email == "[email protected]"
# Test edge cases
def test_empty_input():
with pytest.raises(ValueError):
create_user({})
def test_invalid_email():
with pytest.raises(ValidationError):
create_user({"name": "Bob", "email": "invalid"})
What ships with it
6 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.
- 2d ago First seen · 135 lines · 66 tokens per session scan A 1bcf3b17b0a3
security-testing is a skill published in the GitHub repository d-padmanabhan/agent-engineering-handbook (16 stars, last pushed 6d ago), licensed MIT. It adds 66 tokens to every session and 976 once invoked, about $0.0003 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 2026-09-03.
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