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 magnus919/hermes-profiles --skill arc42-contextgit clone --depth 1 https://github.com/magnus919/hermes-profilesWrote 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/magnus919/hermes-profiles/arc42-context)<a href="https://agentmods.dev/skills/magnus919/hermes-profiles/arc42-context"><img src="https://agentmods.dev/badge/skills/magnus919/hermes-profiles/arc42-context/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/magnus919/hermes-profiles/arc42-context"><img src="https://agentmods.dev/badge/skills/magnus919/hermes-profiles/arc42-context.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 | $0.00089 | $0.00470 |
| Opus 5 | $0.00044 | $0.00235 |
| Sonnet 5 | $0.00018 | $0.00094 |
| Haiku 4.5 | $0.00009 | $0.00047 |
Grade A, and why
arc42-context 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.
What it actually says
arc42 Context
arc42 template for documenting system constraints, context, and quality attributes. arc42 supplies the contextual dimension — constraints and quality attributes — that structure views (C4) and decision records (ADRs) alone don't capture.
arc42-to-Pyramid Mapping
| arc42 Section | Pyramid Layer | Path |
|---|---|---|
| Canvas / Quality tree | L1 (Summary) | 01-summary/quality-tree.md |
| Sections 1-2: Goals, Constraints | L2 (Analysis) | 02-analysis/constraints-and-context.md |
| Section 4: Solution Strategy | L2 (Analysis) | 02-analysis/solution-strategy.md |
| Sections 5-8: Architecture | L3 (Dossiers) | 03-dossiers/arc42-supplemental.md |
| Sections 9-12: Risks, Deployment, Glossary | L3 (Dossiers) | 03-dossiers/arc42-supplemental.md |
Without arc42, an agent sees the solution but not the boundaries that define what constitutes a valid solution. Sections 1-4 in L2 provide the constraint envelope. Sections 5-12 in L3 provide the detailed implementation context.
Contents
references/arc42-sections-1-4.md— detailed guidance per section with example tablesreferences/arc42-to-pyramid-mapping.md— constraints→L2, Canvas→L1, lean/essential/thorough modes
Canonical Reference
- arc42 — https://arc42.org/
- Magnus Hedemark, "Clanker Technical Architect: First on the Scene with Progressive Disclosure" — https://magnus919.com/2026/05/clanker-technical-architect-first-on-the-scene-with-progressive-disclosure/
What ships with it
1 file 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.
- 10d ago First seen · 31 lines · 89 tokens per session scan A 36cd6a377d69
arc42-context is a skill published in the GitHub repository magnus919/hermes-profiles (161 stars, last pushed 2mo ago), licensed MIT. It adds 89 tokens to every session and 470 once invoked, about $0.0004 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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