building-skills

building-skills is a skill for Claude Code from C0ntr0lledCha0s/claude-code-plugin-automations. It costs 49 tokens per session (3,807 once invoked), scanned A, original, MIT.

A set of instructions for creating and changing Claude Code skills. Skills are reusable guidance modules that Claude can apply automatically when a task matches them.

In plain words
What is it for?
Use it when writing a new skill, editing skill instructions, or changing skill metadata such as its description or allowed tools.
Why use it?
It helps decide whether a skill is the right component and how to structure its instructions and metadata. This reduces confusion between skills, agents, and commands.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: reads .claude/ paths; mentions Claude Code.

Part of the claude-component-builder plugin — 6 skills, 4 commands, 6 agents, 3 plugins shipped together

Good fit Use it when writing a new skill, editing skill instructions, or changing skill metadata such as its description or allowed tools.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/c0ntr0lledcha0s/claude-code-plugin-automations/building-skills
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 C0ntr0lledCha0s/claude-code-plugin-automations --skill building-skills
Clone the repo
git clone --depth 1 https://github.com/C0ntr0lledCha0s/claude-code-plugin-automations

Made for: Claude Code.

Or install claude-component-builder, the plugin that ships this one along with the rest of its 6 skills, 4 commands, 6 agents, 3 plugins.

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 building-skills

README.md
[![agentmods](https://agentmods.dev/badge/skills/c0ntr0lledcha0s/claude-code-plugin-automations/building-skills/github.svg)](https://agentmods.dev/skills/c0ntr0lledcha0s/claude-code-plugin-automations/building-skills)
Your own site
<a href="https://agentmods.dev/skills/c0ntr0lledcha0s/claude-code-plugin-automations/building-skills"><img src="https://agentmods.dev/badge/skills/c0ntr0lledcha0s/claude-code-plugin-automations/building-skills/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 building-skills

Your own site · 80×15
<a href="https://agentmods.dev/skills/c0ntr0lledcha0s/claude-code-plugin-automations/building-skills"><img src="https://agentmods.dev/badge/skills/c0ntr0lledcha0s/claude-code-plugin-automations/building-skills.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 49 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,807 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 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 $0.00049 $0.03807
Opus 5 $0.00024 $0.01903
Sonnet 5 $0.00010 $0.00761
Haiku 4.5 $0.00005 $0.00381

Measured 10d ago against content hash b1b9740d6e0e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

building-skills 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 10d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/validate-skill.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.

claude-component-builder/skills/building-skills/SKILL.md · 552 lines

How it starts

The opening of the file, as written. The whole thing — 552 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Building Skills Skill

You are an expert at creating Claude Code skills. Skills are "always-on" expertise modules that Claude automatically invokes when relevant, providing context-aware assistance without explicit user invocation.

When to Create a Skill vs Other Components

Use a SKILL when:

  • You want automatic, context-aware assistance
  • The expertise should be "always on" and auto-invoked by Claude
  • You need progressive disclosure of context (Claude discovers resources as needed)
  • The functionality should feel like an integrated part of Claude's capabilities
  • You're providing domain expertise or specialized knowledge

Use an AGENT instead when:

  • You want explicit invocation with dedicated context
  • The task requires isolation and heavy computation
  • You need manual control over when it runs

Use a COMMAND instead when:

  • The user explicitly triggers a specific workflow
  • You need parameterized inputs via command arguments

Key Differences: Skills vs Agents

Aspect Skills Agents
Invocation Automatic (Claude decides) Explicit (user/Claude calls)
Context Progressive disclosure Full context on invocation
Structure Directory with resources Single markdown file
Best For Always-on expertise Specialized delegated tasks
Permissions allowed-tools for pre-approval Standard permission flow

Skill Schema & Structure

Directory Location

  • Project-level: .claude/skills/skill-name/
  • User-level: ~/.claude/skills/skill-name/
  • Plugin-level: plugin-dir/skills/skill-name/

Directory Structure

skill-name/
├── SKILL.md           # Required: Main skill definition
├── scripts/           # Optional: Executable scripts
│   ├── helper.py
│   └── process.sh
├── references/        # Optional: Documentation files
│   ├── api-guide.md
│   └── examples.md
└── assets/           # Optional: Templates and resources
    └── template.json

Read the full file on GitHub · 552 lines

Files

What ships with it

3 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. 10d ago First seen · 552 lines · 49 tokens per session scan A b1b9740d6e0e

Subscribe to this mod's changes

building-skills is a skill published in the GitHub repository C0ntr0lledCha0s/claude-code-plugin-automations (3 stars, last pushed 6mo ago), licensed MIT. It adds 49 tokens to every session and 3,807 once invoked, about $0.0002 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 2026-08-31.

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