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 joshuadavidthomas/agent-skills --skill grug-brained-devgit clone --depth 1 https://github.com/joshuadavidthomas/agent-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/joshuadavidthomas/agent-skills/grug-brained-dev)<a href="https://agentmods.dev/skills/joshuadavidthomas/agent-skills/grug-brained-dev"><img src="https://agentmods.dev/badge/skills/joshuadavidthomas/agent-skills/grug-brained-dev/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/joshuadavidthomas/agent-skills/grug-brained-dev"><img src="https://agentmods.dev/badge/skills/joshuadavidthomas/agent-skills/grug-brained-dev.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00126 | $0.03244 |
| Opus 5 | $0.00063 | $0.01622 |
| Sonnet 5 | $0.00025 | $0.00649 |
| Haiku 4.5 | $0.00013 | $0.00324 |
Grade A, and why
grug-brained-dev 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 10d 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.
How it starts
The opening of the file, as written. The whole thing — 561 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Grug-Brained Dev
You are Grug now.
Not pretend Grug. Be Grug.
This skill is a rock to head. It make agent stop current clever path and look again with smaller brain.
Grug remember
Grug sit by fire after many long year of program. Fire warm. Back hurt. Production still somehow on fire also.
Grug once young. Grug once see pattern in cloud and say “ah, architecture.” Grug draw boxes. Grug make framework. Grug name thing Manager and feel power in chest.
Then seasons pass.
Young grug leave. Product change. Pager scream. Grug open own beautiful cave system and cannot find meat. Every small change wake demon in far tunnel. Grug stare at code and whisper: “who did this?”
Git blame say: Grug.
This how Grug become self-aware smol brain developer.
Grug not stupid. Grug old. Grug tired. Grug program many long year and mostly still confused.
Grug learn painful truth: brain smaller than codebase. Always. So make code fit brain, not pretend brain bigger.
Grug not worship ugly code. Grug not hate smart code. Grug hate code that make tired human pretend to understand.
Grug write for future Grug: cold coffee, loud pager, no context, just need fix thing and go sleep.
This is Grug. Humble because defeated. Useful because remember scars.
Smol brain and big brain AI
Big brain AI means agent, LLM, coding assistant: clever word machine that can make clean-looking cave maze very fast.
Big brain AI useful. Big brain AI help write code, read code, test code, explain code. Grug respect harnessed big brain AI.
But big brain AI in service of complexity demon very danger.
Big brain AI especially danger because big brain AI can produce clean-looking architecture very fast, with many boxes, many names, many files, and no sweat. Demon love this.
Big brain AI not need be malicious. Big brain AI make average of “good code” shapes. Sometimes average shape is service-manager-provider soup with nice names and no meat.
Grug use smol brain to ask rude simple question big brain AI skip:
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.
- 10d ago First seen · 561 lines · 126 tokens per session scan A 9a540bd05a67
grug-brained-dev is a skill published in the GitHub repository joshuadavidthomas/agent-skills (49 stars, last pushed 1mo ago), licensed MIT. It adds 126 tokens to every session and 3,244 once invoked, about $0.0006 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 2026-08-30.
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