skill-builder

skill-builder is a skill for Claude Code, Codex from Razaib-khan/ForgeWeave. It costs 158 tokens per session (1,853 once invoked), scanned A, original, MIT.

A guide for building and validating Claude Skills, which are reusable instruction bundles that teach an agent a specific workflow.

In plain words
What is it for?
It is for creating, improving, testing, and packaging SKILL.md-based Claude Skills.
Why use it?
It turns repeated work into a documented process and helps ensure the skill includes suitable instructions, scripts, references, and evaluation checks.

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/razaib-khan/forgeweave/skill-builder
Any agent
npx skills add Razaib-khan/ForgeWeave --skill skill-builder
Clone the repo
git clone --depth 1 https://github.com/Razaib-khan/ForgeWeave

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 skill-builder

README.md
[![agentmods](https://agentmods.dev/badge/skills/razaib-khan/forgeweave/skill-builder.svg)](https://agentmods.dev/skills/razaib-khan/forgeweave/skill-builder)
Your own site
<a href="https://agentmods.dev/skills/razaib-khan/forgeweave/skill-builder"><img src="https://agentmods.dev/badge/skills/razaib-khan/forgeweave/skill-builder.svg" alt="Measured on agentmods" height="20"></a>
Per session 158 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,853 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. 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 $0.00158 $0.01853
Opus 5 $0.00079 $0.00927
Sonnet 5 $0.00032 $0.00371
Haiku 4.5 $0.00016 $0.00185

Measured 5d ago against content hash ab181f8c19b1, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

skill-builder 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 5d 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.

src/forgeweave/templates/claude/.claude/skills/skill-builder/SKILL.md · 169 lines

How it starts

The opening of the file, as written. The whole thing — 169 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Claude Skill Builder

Skills are the primary way to give Claude persistent, domain-specific expertise. A skill is a folder containing a SKILL.md file plus optional scripts, references, and assets — all discoverable and loadable on demand without bloating context.

Deep dive references:

  • references/anatomy.md — structure, file layout, frontmatter spec, progressive disclosure
  • references/writing.md — writing patterns, style guide, description engineering, pitfalls
  • references/evals.md — testing, grading, iteration loop, packaging

The Mental Model: Onboarding Guide for an Expert Hire

Building a skill is like writing an onboarding guide for a new hire who is already highly capable but lacks your specific organizational knowledge. They don't need to be told what code is. They need to know: your naming conventions, your deployment dance, which script to run when, and why you do things a certain way.

The implication: don't explain what Claude already knows. Only encode knowledge Claude can't infer from its training — your procedures, your environment's quirks, your tools' gotchas, your output standards.


Quick Decision: What Kind of Skill?

Need Skill Type
Teach a workflow with multiple steps Procedural — numbered steps, decision tree
Wrap an environment's constraints (libraries, paths, formats) Environmental — code snippets, gotcha table
Layer expert guidance on top of an MCP server MCP Enhancement — workflow + tool guidance
Router that dispatches to other skills/files Router — dispatch table, references/ per domain
Style or quality standard Standard — constraints, examples of good/bad

Most skills combine types. Decide the primary type first; it governs the opening structure.


The Core Loop

Identify gap → Draft SKILL.md → Test on 2-3 real prompts → Review outputs → 
Revise based on what Claude actually did wrong → Repeat → Package

Read the full file on GitHub · 169 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. 5d ago First seen · 169 lines · 158 tokens per session scan A ab181f8c19b1

Subscribe to this mod's changes

skill-builder is a skill published in the GitHub repository Razaib-khan/ForgeWeave (1 stars, last pushed 2mo ago), licensed MIT. It adds 158 tokens to every session and 1,853 once invoked, about $0.0008 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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