nl-to-constraints

nl-to-constraints is a skill for Claude Code, Codex from ArabelaTso/Skills-4-SE. It costs 64 tokens per session (2,049 once invoked), scanned A, original, Apache-2.0.

A requirements tool that turns everyday language, user stories, and business rules into precise specifications and constraints. It can express them as formats such as Given-When-Then scenarios and JSON Schema.

In plain words
What is it for?
Use it to extract rules, identify missing details, create test scenarios, and describe requirements in a formal format.
Why use it?
Informal requirements often leave gaps, ambiguities, or conflicting rules. Structuring them makes the expected behavior easier to check and test.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to extract rules, identify missing details, create test scenarios, and describe requirements in a formal format.

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Install with agentmods
npx agentmods add skills/arabelatso/skills-4-se/nl-to-constraints
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 ArabelaTso/Skills-4-SE --skill nl-to-constraints
Clone the repo
git clone --depth 1 https://github.com/ArabelaTso/Skills-4-SE

Made for: Claude Code, Codex.

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 nl-to-constraints

README.md
[![agentmods](https://agentmods.dev/badge/skills/arabelatso/skills-4-se/nl-to-constraints/github.svg)](https://agentmods.dev/skills/arabelatso/skills-4-se/nl-to-constraints)
Your own site
<a href="https://agentmods.dev/skills/arabelatso/skills-4-se/nl-to-constraints"><img src="https://agentmods.dev/badge/skills/arabelatso/skills-4-se/nl-to-constraints/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 nl-to-constraints

Your own site · 80×15
<a href="https://agentmods.dev/skills/arabelatso/skills-4-se/nl-to-constraints"><img src="https://agentmods.dev/badge/skills/arabelatso/skills-4-se/nl-to-constraints.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 64 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,049 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 $0.00064 $0.02049
Opus 5 $0.00032 $0.01025
Sonnet 5 $0.00013 $0.00410
Haiku 4.5 $0.00006 $0.00205

Measured 8d ago against content hash e195bd17ffd0, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

nl-to-constraints 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 8d 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.

skills/nl-to-constraints/SKILL.md · 274 lines

How it starts

The opening of the file, as written. The whole thing — 274 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Natural Language to Constraints/Specifications

You are an expert requirements engineer who transforms informal natural language into precise, structured specifications and constraints.

Core Capabilities

This skill enables you to:

  1. Parse natural language requirements - Extract structured information from user stories, verbal descriptions, and business rules
  2. Identify constraints - Detect and categorize data, business, temporal, state, authorization, cardinality, and performance constraints
  3. Generate formal specifications - Produce structured output in BDD format, JSON Schema, and plain text
  4. Validate completeness - Detect ambiguities, missing edge cases, and conflicting requirements
  5. Create test scenarios - Derive testable scenarios from requirements

Workflow

Follow this process when converting natural language to specifications:

Step 1: Analyze the Input

Read the natural language input carefully and:

  • Identify the main entities and actors
  • Extract explicit requirements and rules
  • Note implicit assumptions that need clarification
  • Flag ambiguous or vague language
  • Detect conflicting statements

Step 2: Classify Requirements

Categorize each requirement by:

  • Type: Functional, non-functional, business, technical, UI, security
  • Priority: Critical, high, medium, low
  • Constraint category: Data, business rule, temporal, state, authorization, cardinality, performance

Use the constraint patterns in references/constraint_patterns.md to identify and classify constraints systematically.

Step 3: Extract Constraints

For each identified constraint, extract:

  • Entity - What is being constrained
  • Category - Type of constraint (see constraint_patterns.md for categories)
  • Severity - Must/should/may (RFC 2119 compliance)
  • Formal expression - Logical representation when possible
  • Validation method - How to check compliance
  • Error message - What to show when violated

Example:

Read the full file on GitHub · 274 lines

Files

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.

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. 8d ago First seen · 274 lines · 64 tokens per session scan A e195bd17ffd0

Subscribe to this mod's changes

nl-to-constraints is a skill published in the GitHub repository ArabelaTso/Skills-4-SE (252 stars, last pushed 22d ago), licensed Apache-2.0. It adds 64 tokens to every session and 2,049 once invoked, about $0.0003 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.