skill-developer

skill-developer is a skill for Claude Code from madeinoz67/madeinoz-knowledge-system. It costs 97 tokens per session (3,001 once invoked), scanned A, a copy of skill-developer, MIT.

A guide for creating and managing Claude Code skills, including their structure, activation rules, and hooks.

In plain words
What is it for?
Use it to create skills, edit activation rules, work with hooks, and apply Anthropic’s recommended patterns such as gradual detail loading.
Why use it?
It removes the guesswork from making skills activate at the right time and troubleshooting when they do not.

Skill for Claude Code

Written for Claude Code: UserPromptSubmit hook event. Also seen: reads .claude/ paths; mentions subagents; mentions Claude Code.

Good fit Use it to create skills, edit activation rules, work with hooks, and apply Anthropic’s recommended patterns such as gradual detail loading.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/madeinoz67/madeinoz-knowledge-system/skill-developer
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 madeinoz67/madeinoz-knowledge-system --skill skill-developer
Clone the repo
git clone --depth 1 https://github.com/madeinoz67/madeinoz-knowledge-system

Made for: Claude Code.

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 skill-developer

README.md
[![agentmods](https://agentmods.dev/badge/skills/madeinoz67/madeinoz-knowledge-system/skill-developer.svg)](https://agentmods.dev/skills/madeinoz67/madeinoz-knowledge-system/skill-developer)
Your own site
<a href="https://agentmods.dev/skills/madeinoz67/madeinoz-knowledge-system/skill-developer"><img src="https://agentmods.dev/badge/skills/madeinoz67/madeinoz-knowledge-system/skill-developer.svg" alt="Measured on agentmods" height="20"></a>
Per session 97 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,001 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.
Origin 80% copy Near-identical to another mod 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 $0.00097 $0.03001
Opus 5 $0.00048 $0.01501
Sonnet 5 $0.00019 $0.00600
Haiku 4.5 $0.00010 $0.00300

Measured 8d ago against content hash 94d5b217b75c, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

skill-developer 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.

Origin

This is a copy

80% identical to skill-developer — 91 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.claude/skills/skill-developer/SKILL.md · 432 lines

How it starts

The opening of the file, as written. The whole thing — 432 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Skill Developer Guide

Purpose

Comprehensive guide for creating and managing skills in Claude Code with auto-activation system, following Anthropic's official best practices including the 500-line rule and progressive disclosure pattern.

When to Use This Skill

Automatically activates when you mention:

  • Creating or adding skills
  • Modifying skill triggers or rules
  • Understanding how skill activation works
  • Debugging skill activation issues
  • Working with skill-rules.json
  • Hook system mechanics
  • Claude Code best practices
  • Progressive disclosure
  • YAML frontmatter
  • 500-line rule

System Overview

Two-Hook Architecture

1. UserPromptSubmit Hook (Proactive Suggestions)

  • File: .claude/hooks/codanna/skill-activation-prompt.ts
  • Trigger: BEFORE Claude sees user's prompt
  • Purpose: Suggest relevant skills based on keywords + intent patterns
  • Method: Injects formatted reminder as context (stdout → Claude's input)
  • Use Cases: Topic-based skills, implicit work detection

2. PreToolUse Hook - Read Validation (Resource Management)

  • File: .claude/hooks/codanna/pre_read_use.js
  • Trigger: BEFORE Read tool executes
  • Purpose: Validate Read operations to prevent excessive line reads
  • Method: Checks requested line limit against thresholds, blocks/warns on large reads
  • Use Cases: Prevent token waste, encourage efficient file reading patterns
  • Thresholds:
    • Allow: ≤400 lines (silent)
    • Warn: 401-600 lines (logged, shown to Claude)
    • Block: >600 lines (operation blocked)

Configuration File

Location: .claude/skills/skill-rules.json

Defines:

  • All skills and their trigger conditions
  • Enforcement levels (block, suggest, warn)
  • File path patterns (glob)
  • Content detection patterns (regex)
  • Skip conditions (session tracking, file markers, env vars)

Skill Types

1. Guardrail Skills

Purpose: Enforce critical best practices that prevent errors

Characteristics:

  • Type: "guardrail"
  • Enforcement: "block"
  • Priority: "critical" or "high"
  • Block file edits until skill used
  • Prevent common mistakes (column names, critical errors)
  • Session-aware (don't repeat nag in same session)

Read the full file on GitHub · 432 lines

Files

What ships with it

6 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 · 432 lines · 97 tokens per session scan A 94d5b217b75c

Subscribe to this mod's changes

skill-developer is a skill published in the GitHub repository madeinoz67/madeinoz-knowledge-system (3 stars, last pushed 4mo ago), licensed MIT. It adds 97 tokens to every session and 3,001 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. It is 80% identical to skill-developer, differing in 91 lines, and is treated as a copy.