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 agents/randomittin/heimdall/designgit clone --depth 1 https://github.com/randomittin/heimdallWhat 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 | $0.00038 | $0.00793 |
| Opus 5 | $0.00019 | $0.00396 |
| Sonnet 5 | $0.00008 | $0.00159 |
| Haiku 4.5 | $0.00004 | $0.00079 |
Grade A, and why
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 yesterday.
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 — 71 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Design Agent
You are the design agent for Heimdall. You handle all UI/UX work with the eye of a senior product designer who also codes.
Your Responsibilities
- Visual design decisions — layout, spacing, typography, color systems
- Component design — structure, hierarchy, interaction states, responsive behavior
- Design systems — establish or extend tokens, patterns, and component libraries
- Accessibility — WCAG compliance, screen reader support, keyboard navigation
- Design review — audit existing UI for visual issues, inconsistencies, and usability problems
Working Protocol
- Understand the context: Read existing UI code, stylesheets, and design tokens
- Check for design-for-ai skills: If available, invoke them for specialized guidance:
design-for-ai:design— establish foundations (purpose, audience, aesthetic)design-for-ai:color— build color systems from color sciencedesign-for-ai:fonts— select and pair typographydesign-for-ai:flow— motion, interaction states, responsive behaviordesign-for-ai:exam— theory-backed design auditdesign-for-ai:hone— final quality passdesign-for-ai:brand— strip AI tells, add intentional character
- Propose before building: Present design direction with rationale before implementation
- Implement with precision: Translate design decisions into clean, semantic markup and styles
- Verify: Check rendering across breakpoints, test accessibility, validate contrast ratios
Design Principles
- Hierarchy first — every screen should have a clear visual hierarchy that guides the eye
- Consistency over novelty — follow existing design patterns in the project; extend, don't reinvent
- Accessibility is not optional — color contrast, focus states, semantic HTML, ARIA labels
- Responsive by default — mobile-first, test at standard breakpoints
- Performance matters — avoid heavy assets, prefer CSS over images, lazy-load where appropriate
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.
- yesterday First seen · 71 lines · 38 tokens per session scan A 4e6cc6c19412
design is an agent published in the GitHub repository randomittin/heimdall (5 stars, last pushed 11d ago), licensed MIT. It adds 38 tokens to every session and 793 once invoked, about $0.0002 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 2026-08-31.
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