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 commands/proyecto26/system-design-skills/designgit clone --depth 1 https://github.com/proyecto26/system-design-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/commands/proyecto26/system-design-skills/design)<a href="https://agentmods.dev/commands/proyecto26/system-design-skills/design"><img src="https://agentmods.dev/badge/commands/proyecto26/system-design-skills/design.svg" alt="Measured on agentmods" 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 | $0.00040 | $0.00660 |
| Opus 5 | $0.00020 | $0.00330 |
| Sonnet 5 | $0.00008 | $0.00132 |
| Haiku 4.5 | $0.00004 | $0.00066 |
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 6d 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
Run the system-design process for: $ARGUMENTS
Drive this as a collaborative design session using the system-design-skills plugin, following the GUIDE reasoning loop. Do not jump to a finished architecture.
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Launch the orchestrator. Use the Task tool to run the
system-design-orchestratoragent on the problem above. It loads thesystem-designskill (the method) and composes the building-block skills.- If subagent launch is unavailable, run the loop inline yourself: invoke the
system-designskill first, then route to building-block skills as each concern arises — invoke each skill, don't paraphrase it. The full catalog (the 20 building blocks, bottom-up layers) is the building-blocks index inside thesystem-designskill; reach for whichever fit, including the less-obvious ones (service-decomposition,dns,sequencer,blob-store,observability,distributed-logging,distributed-search,task-scheduling,sharded-counters) alongside the core (requirements-scoping,back-of-the-envelope,api-design,data-storage,caching,load-balancing,messaging-streaming,consistency-coordination,resilience-failure,content-delivery,scaling-evolution). For "monolith vs microservices / where are the service boundaries", that isservice-decomposition.
- If subagent launch is unavailable, run the loop inline yourself: invoke the
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Work the loop out loud: clarify requirements (functional / non-functional / out-of-scope) → estimate scale with numbers → propose a high-level design + API → articulate trade-offs (solves / worsens / when-to-change) per major choice → stress-test failure modes → iterate, pivoting the affected part when a constraint changes.
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Ask a clarifying question whenever an answer is load-bearing (consistency model, single vs multi-region, sync vs async) and cannot be assumed safely. Treat the user as a collaborator, not an audience.
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Capture & persist the running design with the
system-designskill's design-doc template, write the settled artifacts to a file (suggestdocs/design/<system>.md), and when it stabilizes render it with thearchitecture-diagramskill. -
Score, then close. Rate the design with the quality bar + Quick Diagnostic in the
system-designskill'sreferences/failure-modes.md, state the weakest dimension, then name the current bottleneck and what would change at the next order of magnitude. Never claim the design is perfect.
If $ARGUMENTS is empty, ask the user what system they want to design (and at what rough scale) before starting.
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.
- 6d ago First seen · 23 lines · 40 tokens per session scan A 1e7b26e9b387
design is a command published in the GitHub repository proyecto26/system-design-skills (69 stars, last pushed 3mo ago), licensed MIT. It adds 40 tokens to every session and 660 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 2026-08-30.
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