Declarative language tool for creating complex test data with support for constraints and cross-references.

Install

mkdir -p .claude/skills/vague && curl -L -o skill.zip "https://agentskills.codes/api/skills/download/12325" && unzip -o skill.zip -d .claude/skills/vague && rm skill.zip

Installs to .claude/skills/vague

Activation

This is the description your AI agent reads to decide when to run this skill — the better it matches your request, the more reliably it fires.

Use when writing Vague (.vague) files - a declarative language for generating realistic test data with superposition, constraints, and cross-references
151 chars✓ has a “when” trigger
Intermediate

Key capabilities

  • Define data schemas with various types
  • Specify data superposition for weighted values
  • Set ranges for integer and date fields
  • Define collections with specific item counts
  • Apply constraints to data fields
  • Generate unique and private data fields

How it works

The skill uses a declarative language in .vague files to define schemas, types, superposition, ranges, and constraints, which are then used to generate realistic test data.

Inputs & outputs

You give it
A .vague file defining data schemas and constraints
You get back
Realistic test data generated according to the .vague file

When to use vague

  • Generating mock data
  • Creating test datasets
  • Defining data schemas
  • Validating data structures

About this skill

Vague Language

Quick Start

schema Invoice {
  id: unique int in 1000..9999,
  status: "draft" | "sent" | "paid",
  total: decimal in 100.00..5000.00,
  line_items: 1..5 of LineItem,
  tax: round(total * 0.2, 2),
  assume total > 0
}

dataset TestData {
  invoices: 100 of Invoice
}

Core Syntax

  • Types: string, int, decimal, boolean, date
  • Superposition: "a" | "b" or weighted 0.7: "a" | 0.3: "b"
  • Ranges: int in 1..100, date in 2020..2024
  • Collections: 1..5 of Item or 100 of Item
  • Let bindings: let statuses = "active" | "pending" (reusable values)
  • Computed: total: sum(items.amount), median(), first(), last(), product()
  • Constraints: assume due_date >= issued_date
  • Invariants: invariant amount > 0 "message" (never violated, even in violating mode)
  • Contracts: contract Name { invariant ... } applied via schema X implements Name
  • Refine: } refine { if type == "A" { field: int in 1..10 } }
  • Match: match status { "a" => "Alpha", "b" => "Beta" }
  • References: any of companies where .active == true
  • Parent ref: = ^parent_field
  • Nullable: string? or string | null
  • Unique: id: unique int in 1..1000
  • Private: age: private int (generated but excluded from output)
  • Ordered: [48, 52, 55, 60] (cycles through values)
  • Conditional: field: string when condition (field only exists if condition is true)

Reference Files

When not to use it

  • When generating data without schemas or constraints
  • When simple random data generation is sufficient
  • When working with data that does not require cross-references

Limitations

  • Requires knowledge of Vague language syntax
  • Focuses on generating test data
  • Does not infer data relationships not explicitly defined

How it compares

This skill provides a declarative and structured way to generate complex test data with specific constraints and relationships, unlike simple data generation tools.

Compared to similar skills

vague side by side with the closest alternatives in the catalog.

SkillInstallsUpdatedSafetyDifficulty
vague (this skill)07moNo flagsIntermediate
backtesting-frameworks172moNo flagsAdvanced
evaluating-machine-learning-models127dReviewIntermediate
evaluate-environments126dReviewIntermediate

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Example prompts that trigger this skill in your AI assistant.

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