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 sd0xdev/sd0x-harness --skill best-practicesgit clone --depth 1 https://github.com/sd0xdev/sd0x-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/sd0xdev/sd0x-harness/best-practices)<a href="https://agentmods.dev/skills/sd0xdev/sd0x-harness/best-practices"><img src="https://agentmods.dev/badge/skills/sd0xdev/sd0x-harness/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/sd0xdev/sd0x-harness/best-practices"><img src="https://agentmods.dev/badge/skills/sd0xdev/sd0x-harness/best-practices.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 1 finding, up to medium
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 →
- medium Agent Snooping · line 102 Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.
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 | $0.00101 | $0.02302 |
| Opus 5.5 | $0.00040 | $0.00921 |
| Sonnet 5.5 | $0.00020 | $0.00460 |
| Haiku 4.5 | $0.00010 | $0.00230 |
Grade A, and why
best-practices scanned grade A with 1 finding 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.
Enumerates other installed skillslowAgent snooping
Other skills' SKILL.md files reveal prompts, capabilities and secrets that should be invisible to peers.
> **agent-browser detection**: Attempt `Skill("agent-browser", ...)` first. If error (not installed), fall through to Priority 2. Filesystem check (`ls .claude/skills/agent-browser`) is diagnostic only — may give false n Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.
How it starts
The opening of the file, as written. The whole thing — 196 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Best Practices Audit
Supplementary Agent
Dispatch performance dimension analysis:
Agent({
description: "Analyze performance-related best practices compliance",
subagent_type: "performance-optimizer",
prompt: Analyze codebase for performance best practices related to: <topic> Check for N+1 queries, memory leaks, blocking operations, and caching issues.
})
Non-Negotiable Rules (Normative Source)
SKILL.md is the normative source for these rules. Reference files elaborate but do not override.
| # | Rule | Violation = |
|---|---|---|
| 1 | Phase 0 Comprehension Gate: Before any Phase 1–4 investigative call, output the audit plan block (see command definition) | Audit invalid |
| 2 | Phase 3 must invoke /codex-brainstorm via Skill tool — a raw transport debate is invalid |
Audit invalid |
| 3 | Phase 4 must include Debate threadId (non-empty, from Phase 3 session) |
Report rejected |
| 4 | Phase 4 must include Debate Conclusion referencing specific Phase 3 rounds (not blank, not placeholder) |
Report rejected |
Trigger
- Keywords: best practices audit, industry standards check, compliance audit, benchmark compliance, practice alignment, standards verification
- User has a current target (repo/service/module) to audit against standards
- Intent is conformance judgment (OK/WARN/FAIL), not open-ended exploration
When NOT to Use
| Scenario | Alternative |
|---|---|
| Broad research / discovery / multi-source exploration | /deep-research |
| Pure code review | /codex-review-fast |
| Architecture design | /codex-architect |
| Security-only audit | /codex-security |
MECE boundary:
/best-practicesproduces a conformance judgment (verdict + gap + debate proof)./deep-researchproduces a discovery synthesis (claim registry + coverage matrix + score). "What are best approaches for X?" ->/deep-research. "Does our code follow best practices for X?" ->/best-practices.
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.
- 1mo ago Changed 08cb8f5ced33
- 1mo ago First seen · 196 lines · 101 tokens per session scan A 2f492b5f632e
best-practices is a skill published in the GitHub repository sd0xdev/sd0x-harness (194 stars, last pushed 14d ago), licensed MIT. It adds 101 tokens to every session and 2,302 once invoked, about $0.0004 per session on Opus 5.5. A static security scan graded it A with 1 finding (enumerates other installed skills). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
Other skills, from other repositories
code-review
Two-mode skill: (1) adversarial review — spec compliance + code quality + security, confidence-scored findings with file:line evidence; (2) receiving review — verify-before- agreeing discipline for acting on external/human review feedback.
codebase-hygiene
Two-mode skill: (1) find semantic duplicates — functions doing the same thing under different names, invisible to copy-paste detectors; (2) deepen shallow modules — thin wrappers and pass-through layers that spread complexity. Advisory and read-only; changes route through BUILD with full gates.
evaluator-review-contract
Internal Auto-Harness evaluator skill for sprint contract review before implementation. Use only inside the Evaluator subagent during review mode.
comet-review
A read-only review guide for checking the current Comet change, a managed software-change workflow. It focuses on correctness, security, and boundary problems without changing files or advancing the workflow.
comet-github-pr-review
A read-only review process for pull requests in Comet's GitHub repositories. A pull request is a proposed code change; the review checks its current code, related issue, comments, merge status, and automated checks.
exploration
Two-mode exploration skill: (1) design dialogue — turn rough ideas into validated designs through collaborative interview before planning; (2) spike — throwaway code answering ONE design question, deleted or absorbed, never shipped. Router invokes mode via dispatch context.