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 timwukp/agent-skills-best-practice --skill user-story-writinggit clone --depth 1 https://github.com/timwukp/agent-skills-best-practiceWrote 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/timwukp/agent-skills-best-practice/user-story-writing)<a href="https://agentmods.dev/skills/timwukp/agent-skills-best-practice/user-story-writing"><img src="https://agentmods.dev/badge/skills/timwukp/agent-skills-best-practice/user-story-writing/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/timwukp/agent-skills-best-practice/user-story-writing"><img src="https://agentmods.dev/badge/skills/timwukp/agent-skills-best-practice/user-story-writing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00083 | $0.00897 |
| Opus 5 | $0.00042 | $0.00449 |
| Sonnet 5 | $0.00017 | $0.00179 |
| Haiku 4.5 | $0.00008 | $0.00090 |
Grade A, and why
user-story-writing 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 12d 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 — 79 lines — stays where its author put it; the contents beside it link to each section on GitHub.
User Story Writing
Turn requirements, feature ideas, and epics into stories a team can estimate and deliver. The product is the story set, not prose about the feature.
Story Format
### [ID] [Title — verb phrase, outcome-oriented]
**As a** [specific user role — not "user"], **I want to** [action], **so that** [value the role actually cares about].
#### Acceptance Criteria
- Given [precondition], when [action], then [observable outcome]
- ...
For system-level or compliance-driven requirements where the persona format gets artificial, use EARS instead:
| EARS pattern | Template | Use for |
|---|---|---|
| Ubiquitous | The [system] shall [behavior] | Invariants |
| Event-driven | When [trigger], the [system] shall [behavior] | Responses to events |
| State-driven | While [state], the [system] shall [behavior] | Mode-dependent behavior |
| Unwanted behavior | If [undesired condition], then the [system] shall [behavior] | Error and abuse handling |
| Optional | Where [feature is included], the [system] shall [behavior] | Configurable capabilities |
INVEST Check
Run every story against INVEST before delivering; fix violations rather than annotating them:
- Independent — schedulable without forcing another story into the same sprint
- Negotiable — captures intent, not implementation; the "how" stays open
- Valuable — the "so that" names value for the role; "so that the database is updated" fails
- Estimable — a developer could size it; unknowns extracted into spike stories
- Small — fits comfortably in a sprint; otherwise split (see below)
- Testable — every criterion observable; "works correctly" fails
Epic Splitting Patterns
Apply the first pattern that yields shippable slices:
- By workflow step — each step of the user journey is a story (browse → select → pay → confirm).
- Happy path first — story 1 is the simplest successful flow; error handling, edge cases, and limits follow as separate stories.
- By business rule — base behavior first, each rule variation (discounts, regions, roles) its own story.
- By data variation — support one input type first (e.g. domestic transfers), add types incrementally.
- CRUD split — create first, then read/update/delete if each carries real value.
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.
- 12d ago First seen · 79 lines · 83 tokens per session scan A 66d42fc6e724
user-story-writing is a skill published in the GitHub repository timwukp/agent-skills-best-practice (10 stars, last pushed 2d ago), licensed MIT. It adds 83 tokens to every session and 897 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 2026-08-31.
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