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 aj-geddes/useful-ai-prompts --skill mobile-first-designgit clone --depth 1 https://github.com/aj-geddes/useful-ai-promptsWrote 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/aj-geddes/useful-ai-prompts/mobile-first-design)<a href="https://agentmods.dev/skills/aj-geddes/useful-ai-prompts/mobile-first-design"><img src="https://agentmods.dev/badge/skills/aj-geddes/useful-ai-prompts/mobile-first-design/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/aj-geddes/useful-ai-prompts/mobile-first-design"><img src="https://agentmods.dev/badge/skills/aj-geddes/useful-ai-prompts/mobile-first-design.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket pass
- Snyk 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 | $0.00028 | $0.00568 |
| Opus 5.5 | $0.00011 | $0.00227 |
| Sonnet 5.5 | $0.00006 | $0.00114 |
| Haiku 4.5 | $0.00003 | $0.00057 |
Grade A, and why
mobile-first-design 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 2mo 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 — 101 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Mobile-First Design
Table of Contents
Overview
Mobile-first design prioritizes small screens as the starting point, ensuring core functionality works on all devices while leveraging larger screens for enhanced experience.
When to Use
- Web application design
- Responsive website creation
- Feature prioritization
- Performance optimization
- Progressive enhancement
- Cross-device experience design
Quick Start
Minimal working example:
Mobile-First Approach:
Step 1: Design for Mobile (320px - 480px)
- Constrained space forces priorities
- Focus on essential content and actions
- Single column layout
- Touch-friendly interactive elements
Step 2: Enhance for Tablet (768px - 1024px)
- Add secondary content
- Multi-column layouts possible
- Optimize spacing and readability
- Take advantage of hover states
Step 3: Optimize for Desktop (1200px+)
- Full-featured experience
- Advanced layouts
- Rich interactions
- Multiple columns and sidebars
---
## Responsive Breakpoints:
Mobile: 320px - 480px
- iPhone SE, older phones
// ... (see reference guides for full implementation)
Reference Guides
Detailed implementations in the references/ directory:
| Guide | Contents |
|---|---|
| Responsive Design Implementation | Responsive Design Implementation |
| Mobile Performance | Mobile Performance |
| Progressive Enhancement | Progressive Enhancement |
Best Practices
✅ DO
- Design for smallest screen first
- Test on real mobile devices
- Use responsive images
- Optimize for mobile performance
- Make touch targets 44x44px minimum
- Stack content vertically on mobile
- Use hamburger menu on mobile
- Hide non-essential content on mobile
- Test with slow networks
- Progressive enhancement approach
What ships with it
5 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.
- 2mo ago First seen · 101 lines · 28 tokens per session scan A d895f3fa6b6b
mobile-first-design is a skill published in the GitHub repository aj-geddes/useful-ai-prompts (376 stars, last pushed 8mo ago), licensed MIT. It adds 28 tokens to every session and 568 once invoked, about $0.0001 per session on Opus 5.5. 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.
mobile-first-design compared with skills from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| mobile-first-designaj-geddes/useful-ai-prompts | Skill | 376 | 8mo ago | MIT | A | 28 | Claude Code, Codex |
| anti-slop-designsickn33/agentic-awesome-skills | Skill | 49k | yesterday | MIT | A | 34 | Claude Code |
| chakra-ui-builderchakra-ui/chakra-ui | Skill | 41k | yesterday | MIT | A | 214 | Claude Code, Codex |
| visual-ralphYeachan-Heo/oh-my-codex | Skill | 34k | 3d ago | MIT | A | 52 | Codex |
| open-design-setupcompozy/compozy | Skill | 2.8k | yesterday | MIT | A | 67 | Claude Code, Codex |
| frontend-visual-qadaymade/claude-code-skills | Skill | 1.5k | yesterday | MIT | A | 125 | Claude Code, Codex |
| prototype-webnexu-io/html-anything | Skill | 9.4k | 25d ago | Apache-2.0 | A | 24 | Claude Code, Codex |