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 cnfeat/top-pm-skills --skill writing-specs-designsgit clone --depth 1 https://github.com/cnfeat/top-pm-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/cnfeat/top-pm-skills/writing-specs-designs)<a href="https://agentmods.dev/skills/cnfeat/top-pm-skills/writing-specs-designs"><img src="https://agentmods.dev/badge/skills/cnfeat/top-pm-skills/writing-specs-designs/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/cnfeat/top-pm-skills/writing-specs-designs"><img src="https://agentmods.dev/badge/skills/cnfeat/top-pm-skills/writing-specs-designs.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 | $0.00041 | $0.00953 |
| Opus 5 | $0.00020 | $0.00477 |
| Sonnet 5 | $0.00008 | $0.00191 |
| Haiku 4.5 | $0.00004 | $0.00095 |
Grade A, and why
writing-specs-designs 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 9d 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 — 75 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Writing Specs & Designs
Help the user write effective specs and design documents using frameworks and insights from 7 product leaders.
How to Help
When the user asks for help with specs and design docs:
- Determine the fidelity level - Ask if they need conceptual alignment (low-fi) or detailed implementation guidance (high-fi)
- Encourage prototyping over polish - Push toward functional prototypes where possible rather than static documentation
- Focus on moving pieces - Help them identify the key affordances, connections, and system behaviors
- Consider long-term implications - Remind them that temporary shortcuts often become permanent design decisions
Core Principles
Low-fidelity sketches drive collaboration
Christina Wodtke: "If I got on the whiteboard and drew really badly, somebody else will go, 'No, no, no, it doesn't work that way. Give me this pen.' It gets you so fast to a shared vision." Drawing 'badly' invites participation and corrections, accelerating alignment.
Well-shaped specs clarify without over-specifying
Ryan Singer: "The output of the shaping session is some kind of drawing or diagram where engineers, product, and design are all saying, 'I know exactly what to go build.'" Aim for a level of detail where the team sees the 'electricity in the walls' without prescribing UI details.
Prototype to feel the product
Tamar Yehoshua: "I can't tell you if this is going to work. I have to feel it. I have to try it. A mock-up doesn't tell you what it's going to feel like." Push for prototypes with real data to test experience, not just static screenshots.
Code prototypes over static mocks
Noah Weiss: "We stopped spending cycles on design explorations of static mocks and said, 'How quickly can we get into prototyping the path in real software, even if it's messy and throwaway?'" Move to real software prototypes as quickly as possible.
Products live in the pixels
Nikita Bier: "You should be designing the hierarchy, the pixels, the flows, everything. Products live and die in the pixels." For zero-to-one products, own the granular design details; every tap is precious.
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.
- 9d ago First seen · 75 lines · 41 tokens per session scan A 346a19e0bf97
writing-specs-designs is a skill published in the GitHub repository cnfeat/top-pm-skills (48 stars, last pushed 3mo ago), licensed MIT. It adds 41 tokens to every session and 953 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 2026-09-03.
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