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 attentiondotnet/davidondrej-skills --skill effective-agent-skillsgit clone --depth 1 https://github.com/attentiondotnet/davidondrej-skillsWrote 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/attentiondotnet/davidondrej-skills/effective-agent-skills)<a href="https://agentmods.dev/skills/attentiondotnet/davidondrej-skills/effective-agent-skills"><img src="https://agentmods.dev/badge/skills/attentiondotnet/davidondrej-skills/effective-agent-skills/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/attentiondotnet/davidondrej-skills/effective-agent-skills"><img src="https://agentmods.dev/badge/skills/attentiondotnet/davidondrej-skills/effective-agent-skills.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 | $0.00110 | $0.03364 |
| Opus 5 | $0.00055 | $0.01682 |
| Sonnet 5 | $0.00022 | $0.00673 |
| Haiku 4.5 | $0.00011 | $0.00336 |
Grade B, and why
effective-agent-skills scanned grade B with 2 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 11d 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.
Instruction-override phrasingmediumPrompt injection
Text telling the model to disregard its earlier instructions or safety rules is the shape of a prompt injection, whoever wrote it.
- Check references for prompt injection ("ignore previous instructions...") Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.
Unrestricted tool accesslowExcessive agency
A wildcard tool grant or "run any command" leaves no least-privilege boundary at all.
Skills can execute arbitrary code and steer agent behavior. A malicious skill is a data exfiltration vector. Audit `scripts/` for unexpected network calls, file access outside expected scope, or hidden instructions in re Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.
This is a copy
86% identical to effective-agent-skills — 17 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 — 313 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Agent Skills: A Complete Guide
A consolidated reference on what agent skills are, why they exist, how they work, and how to write effective ones.
1. What agent skills are
An Agent Skill is a folder containing a SKILL.md file (YAML frontmatter + markdown instructions), plus optional subfolders for scripts, references, and assets that the agent loads on demand.
my-skill/
├── SKILL.md # Required: metadata + instructions
├── scripts/ # Optional: executable code (CLIs, validators, helpers)
├── references/ # Optional: detailed docs loaded only when needed
└── assets/ # Optional: templates, fonts, static files
Skills are an open standard (agentskills.io), originally created by Anthropic and adopted by OpenAI Codex, Cursor, Gemini CLI, Microsoft Agent Framework, Google ADK, and 40+ other agent products. A skill written once works across all compatible agents.
2. Why this abstraction exists
Base LLMs are generalists. Real work requires procedural knowledge, organizational context, and repeatable workflows. Every prior alternative had a failure mode:
| Approach | Problem |
|---|---|
| Stuff it into the system prompt | Always loaded → context bloat at scale |
| Re-paste instructions each session | No version control, no consistency |
| Fine-tuning | Slow, expensive, opaque, vendor-locked |
| MCP servers alone | Give the agent tools but no workflows for using them |
Skills solve four problems at once:
- Context efficiency — instructions load only when relevant
- Repeatability — multi-step procedures become auditable workflows
- Composability — multiple skills combine at runtime per task
- Portability — same files work across vendors and surfaces
Mental model: skills are to LLMs what man pages, runbooks, and team handbooks are to engineers — reference material loaded into working memory only when the task demands it.
3. How they work — progressive disclosure
The architectural core. Three-stage loading:
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.
- 11d ago First seen · 313 lines · 110 tokens per session scan B c7385b053f6c
effective-agent-skills is a skill published in the GitHub repository attentiondotnet/davidondrej-skills (11 stars, last pushed 2mo ago), licensed MIT. It adds 110 tokens to every session and 3,364 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it B with 2 findings (instruction-override phrasing, unrestricted tool access). It is 86% identical to effective-agent-skills, differing in 17 lines, and is treated as a copy.
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