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 vadimcomanescu/codex-skills --skill feature-design-assistantgit clone --depth 1 https://github.com/vadimcomanescu/codex-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/vadimcomanescu/codex-skills/feature-design-assistant)<a href="https://agentmods.dev/skills/vadimcomanescu/codex-skills/feature-design-assistant"><img src="https://agentmods.dev/badge/skills/vadimcomanescu/codex-skills/feature-design-assistant/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/vadimcomanescu/codex-skills/feature-design-assistant"><img src="https://agentmods.dev/badge/skills/vadimcomanescu/codex-skills/feature-design-assistant.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 | $0.00036 | $0.00290 |
| Opus 5.5 | $0.00014 | $0.00116 |
| Sonnet 5.5 | $0.00007 | $0.00058 |
| Haiku 4.5 | $0.00004 | $0.00029 |
Grade A, and why
feature-design-assistant 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 1mo 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
Feature Design Assistant
Turn ideas into implementable specs with clear scope, risks, and acceptance criteria.
Workflow
- Context: skim the repo for patterns, modules, and recent changes.
- Discovery: ask up to 4 questions per round.
- Design: propose a solution with trade-offs.
- Spec: write a short design doc with sections below.
Discovery Questions (examples)
- Goal and primary users?
- Scope and timeline constraints?
- Which layers are touched (data, API, UI, infra)?
- Quality bar (performance, security, reliability)?
- Non-goals / out-of-scope?
Design Doc Template
- Problem
- Goals / Non-goals
- Proposed solution (components, data flow)
- Alternatives (and why rejected)
- Risks / Open questions
- Testing / rollout plan
- Acceptance criteria
Guardrails
- Keep scope tight; call out what is explicitly excluded.
- Prefer existing patterns unless the user asks to change architecture.
- If the change is large, propose a phased rollout.
References
- Extended examples:
references/examples.md
What ships with it
2 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.
- 1mo ago First seen · 40 lines · 36 tokens per session scan A dfd5e4fd2925
feature-design-assistant is a skill published in the GitHub repository vadimcomanescu/codex-skills (25 stars, last pushed 9mo ago), licensed MIT. It adds 36 tokens to every session and 290 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 2026-08-30.
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