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use-case-spec

use-case-spec is a skill for Claude Code from AI-Unified-Process/marketplace. It costs 155 tokens per session (2,188 once invoked), scanned A, original, Apache-2.0.

A document-writing guide for describing a complete use case: how an actor uses a system to reach a goal. It includes starting conditions, the normal path, alternatives, ending conditions, and business rules.

In plain words
What is it for?
Use it to write or update functional use case documents in the required project format, such as login, account registration, or order placement scenarios.
Why use it?
It turns a feature or interaction into a consistent specification that developers and other stakeholders can follow and review.

Skill for Claude Code

Written for Claude Code: $ARGUMENTS substitution. Also seen: names the TodoWrite tool.

Part of the aiup-core plugin — 6 skills shipped together

not rated 123repo +3 12d ago A scan SkillSpector: pass 155 tokens original Apache-2.0

Good fit Use it to write or update functional use case documents in the required project format, such as login, account registration, or order placement scenarios.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/ai-unified-process/marketplace/use-case-spec
View source ↗ AI-Unified-Process/marketplace
Install

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.

Any agent
npx skills add AI-Unified-Process/marketplace --skill use-case-spec
Clone the repo
git clone --depth 1 https://github.com/AI-Unified-Process/marketplace

Made for: Claude Code.

Or install aiup-core, the plugin that ships this one along with the rest of its 6 skills.

Wrote 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.

agentmods badge for use-case-spec

README.md
[![agentmods](https://agentmods.dev/badge/skills/ai-unified-process/marketplace/use-case-spec/github.svg)](https://agentmods.dev/skills/ai-unified-process/marketplace/use-case-spec)
Your own site
<a href="https://agentmods.dev/skills/ai-unified-process/marketplace/use-case-spec"><img src="https://agentmods.dev/badge/skills/ai-unified-process/marketplace/use-case-spec/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.

agentmods 80×15 button for use-case-spec

Your own site · 80×15
<a href="https://agentmods.dev/skills/ai-unified-process/marketplace/use-case-spec"><img src="https://agentmods.dev/badge/skills/ai-unified-process/marketplace/use-case-spec.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 155 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,188 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00155 $0.02188
Opus 5 $0.00077 $0.01094
Sonnet 5 $0.00031 $0.00438
Haiku 4.5 $0.00015 $0.00219

Measured 11d ago against content hash 81d32e88ecd2, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

use-case-spec 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 11d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/validate_use_case.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

aiup-core/skills/use-case-spec/SKILL.md · 164 lines

How it starts

The opening of the file, as written. The whole thing — 164 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Use Case Specification

Instructions

Create or update use case specification documents for $ARGUMENTS in docs/use_cases/. Each use case describes a complete interaction between an actor and the system to achieve a goal.

File naming (do this exactly)

One file per use case, written to docs/use_cases/UC-XXX-<kebab-case-name>.md where:

  • UC-XXX is the use case's three-digit ID (e.g. UC-001).
  • <kebab-case-name> is the use case name taken verbatim from the use case diagram (docs/use_cases.puml), lowercased with spaces replaced by hyphens. Do not paraphrase, expand, or reorder the words.
Use case name in diagram Correct filename
Register Account docs/use_cases/UC-001-register-account.md
Log In docs/use_cases/UC-002-log-in.md
Place Order docs/use_cases/UC-001-place-order.md

Scope: one or many use cases

  • If the task names a single use case (e.g. "write UC-001 Place Order"), produce only that one file. Do not create specs for other use cases in the diagram.
  • If the task asks for "all use cases" or names several, produce one file per use case:
    • UC-XXX IDs come from the diagram and never repeat.
    • BR-XXX business-rule IDs are unique within their own file only and restart at BR-001 in every file — the use case is the namespace. When referring to a rule of another use case, qualify it with the use case id (e.g. "UC-005 BR-002"), never by the bare rule id.

DO NOT

  • Write vague or incomplete scenarios
  • Skip numbering steps in the Main Success Scenario
  • Omit alternative flows for error conditions
  • Leave postconditions undefined
  • Mix multiple use cases in one document
  • Use technical implementation details in the flow steps

Read the full file on GitHub · 164 lines

Files

What ships with it

4 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.

Changes

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.

  1. 11d ago First seen · 164 lines · 155 tokens per session scan A 81d32e88ecd2

Subscribe to this mod's changes

use-case-spec is a skill published in the GitHub repository AI-Unified-Process/marketplace (123 stars, last pushed 12d ago), licensed Apache-2.0. It adds 155 tokens to every session and 2,188 once invoked, about $0.0008 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.

Writing and docs
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