aigent-builder

A skill-generation workflow that creates SKILL.md files and their folders from a plain-language description. SKILL.md is the instruction file an agent skill uses to describe its behavior.

In plain words
What is it for?
Use it to scaffold new agent skills, generate their instruction files, and check that they follow the stated skill format.
Why use it?
It removes the need to design the folder structure and required metadata by hand, and can validate the generated result.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/wkusnierczyk/aigent/aigent-builder
Any agent
npx skills add wkusnierczyk/aigent --skill aigent-builder
Clone the repo
git clone --depth 1 https://github.com/wkusnierczyk/aigent

Made for: Claude Code, Codex.

Per session 58 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 553 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 1 finding. Scan, not verified.
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 $0.00058 $0.00553
Opus 5 $0.00029 $0.00277
Sonnet 5 $0.00012 $0.00111
Haiku 4.5 $0.00006 $0.00055

Measured 2d ago against content hash 3e2d1d67f685, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade B, and why

aigent-builder scanned grade B with 1 finding 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 2d 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.

Enumerates other installed skillsmediumAgent snooping

Other skills' SKILL.md files reveal prompts, capabilities and secrets that should be invisible to peers.

aigent new "<purpose>" --dir .claude/skills/<name>/
skills/aigent-builder/SKILL.md · 94 lines

What it actually says

Skill Builder

Setup

Check if aigent is available:

command -v aigent

With aigent CLI

If aigent is on $PATH, use the CLI for authoritative skill generation:

  1. Build the skill:

    aigent new "<purpose>" --dir .claude/skills/<name>/
    
  2. Validate the result:

    aigent validate .claude/skills/<name>/
    
  3. If validation reports errors, fix the SKILL.md and re-validate.

Use --no-llm to force deterministic mode (no API keys needed). Use --name <name> to override the derived skill name.

The CLI defaults to outputting in ./<name>/ in the current directory. The --dir flag above overrides this to place skills in .claude/skills/, which is the standard Claude Code skill location.

Without aigent CLI

If aigent is not available, generate the SKILL.md directly.

Name rules

  • Lowercase letters, numbers, and hyphens only
  • Maximum 64 characters
  • Prefer gerund form: "processing-pdfs", "analyzing-data"
  • No reserved words: "anthropic", "claude"
  • No XML tags
  • Must match directory name

Description rules

  • Non-empty, maximum 1024 characters
  • Third person: "Processes PDFs..." not "I process PDFs..."
  • Include what the skill does AND when to use it
  • No XML tags

Body guidelines

  • Keep under 500 lines
  • Be concise — only add context Claude doesn't already have
  • Use ## headings for sections
  • Link to additional files for large content

Output

Write the SKILL.md to .claude/skills/<name>/SKILL.md with:

---
name: <kebab-case-name>
description: <what-it-does-and-when-to-use-it>
---

# <Title>

## Quick start

[Concise instructions]

## Usage

[Detailed usage]
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. 2d ago First seen · 94 lines · 58 tokens per session scan B 3e2d1d67f685

Subscribe to this mod's changes

aigent-builder is a skill published in the GitHub repository wkusnierczyk/aigent (4 stars, last pushed 6mo ago), licensed Apache-2.0. It adds 58 tokens to every session and 553 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it B with 1 finding (enumerates other installed skills). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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