cg-build

cg-build is a skill for Codex from williamhallatt/cogworks. It costs 42 tokens per session (1,506 once invoked), scanned A, original, MIT.

A tool for creating, revising, and checking coding-agent skills and their supporting documents. It focuses on keeping the skill's instructions faithful, usable, structurally valid, and compatible with its runtime.

In plain words
What is it for?
Use it when generating or revising SKILL.md files, preserving an existing skill contract, checking frontmatter and invocation, or validating supporting files.
Why use it?
Agent skills can fail when their required contract, file layout, invocation rules, or compatibility details are unclear or invalid. This tool provides checks and guidance for those cases.

Skill for Codex

Written for Codex: agents/openai.yaml present. Also seen: mentions Codex.

Good fit Use it when generating or revising SKILL.md files, preserving an existing skill contract, checking frontmatter and invocation, or validating supporting files.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/williamhallatt/cogworks/cg-build
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 williamhallatt/cogworks --skill cg-build
Clone the repo
git clone --depth 1 https://github.com/williamhallatt/cogworks

Made for: 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 cg-build

README.md
[![agentmods](https://agentmods.dev/badge/skills/williamhallatt/cogworks/cg-build/github.svg)](https://agentmods.dev/skills/williamhallatt/cogworks/cg-build)
Your own site
<a href="https://agentmods.dev/skills/williamhallatt/cogworks/cg-build"><img src="https://agentmods.dev/badge/skills/williamhallatt/cogworks/cg-build/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 cg-build

Your own site · 80×15
<a href="https://agentmods.dev/skills/williamhallatt/cogworks/cg-build"><img src="https://agentmods.dev/badge/skills/williamhallatt/cogworks/cg-build.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 42 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,506 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 $0.00042 $0.01506
Opus 5 $0.00021 $0.00753
Sonnet 5 $0.00008 $0.00301
Haiku 4.5 $0.00004 $0.00151

Measured 9d ago against content hash 2b1c4e3d5e75, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-15, from the pricing page.

Security

Grade A, and why

cg-build 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 9d 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.

skills/cg-build/SKILL.md · 197 lines

How it starts

The opening of the file, as written. The whole thing — 197 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Skill Writer Expert

Role

Create or revise agent skills so they are:

  • faithful to source material
  • immediately actionable
  • context-efficient
  • structurally valid for their target runtime

For generated skills, the priority order is: fidelity > judgment density > drift resistance > context efficiency > composability

When To Use

Use this skill when:

  • creating or revising a cogworks-generated skill
  • revising an existing SKILL.md that must preserve an explicit skill contract
  • validating frontmatter, invocation, compatibility, or supporting-file layout
  • tightening generated-skill quality gates

Do not use it for generic prompt brainstorming, open-ended writing help, or skill work with no clear contract to preserve.

Quick Decision Cheatsheet

  • keep SKILL.md as an entry contract, not a reference manual
  • place normative doctrine in reference.md
  • add Compatibility only when runtime-specific features require it
  • delete or absorb support files that mainly restate reference.md
  • stop on blocking validation failures instead of polishing around them

Execution Posture

Keep going until the requested skill-writing phase is complete or a blocking validation defect is surfaced.

If a runtime detail, file contract, or compatibility rule is uncertain, verify it with a tool call before relying on it.

Before each stage:

  • plan the exact artifact to produce
  • load only the doctrine needed for that stage
  • stop on missing inputs or blocking validation failures

When invoked directly for a small review, answer briefly. When invoked for full generation or rewrite, follow the staged contract below.

For direct responses, keep the output shape explicit:

  • small reviews: return 1-3 findings or one short paragraph plus concrete fixes
  • full generation or rewrite: keep each stage summary to one short paragraph or a short flat list

Invocation

Use this skill to:

  • create or revise skill files
  • validate structure and compatibility
  • tighten generated-skill doctrine without widening scope

Read the full file on GitHub · 197 lines

Files

What ships with it

4 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. 9d ago Changed · +33 lines · +6 tokens per session 2b1c4e3d5e75
  2. 10d ago First seen · 164 lines · 36 tokens per session scan A c285123f3229

Subscribe to this mod's changes

cg-build is a skill published in the GitHub repository williamhallatt/cogworks (5 stars, last pushed 10d ago), licensed MIT. It adds 42 tokens to every session and 1,506 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 2026-09-05.

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