A guide for creating and maintaining Agent Skills with Bun, a JavaScript and TypeScript runtime. It covers skill files, scripts, dependencies, tests, and repository layout.

Building, editing, testing, and maintaining Agent Skills in repositories that use Bun.

It helps keep new or changed skills organized and consistent with the project's development conventions.

skill-dev — Skill for Claude Code and Codex by TimBeyer/agent-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 TimBeyer/agent-skills --skill skill-dev

Clone the repo

git clone --depth 1 https://github.com/TimBeyer/agent-skills

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/timbeyer/agent-skills/skill-dev/github.svg)](https://agentmods.dev/skills/timbeyer/agent-skills/skill-dev)

Your own site

<a href="https://agentmods.dev/skills/timbeyer/agent-skills/skill-dev"><img src="https://agentmods.dev/badge/skills/timbeyer/agent-skills/skill-dev/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/timbeyer/agent-skills/skill-dev"><img src="https://agentmods.dev/badge/skills/timbeyer/agent-skills/skill-dev.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 3,356 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 unknown 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.

Model	Per session	Once invoked
Fable 5.1	$0.00042	$0.03356
Opus 5.5	$0.00017	$0.01342
Sonnet 5.5	$0.00008	$0.00671
Haiku 4.5	$0.00004	$0.00336

Measured 2mo ago against content hash 57803110b947, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

skill-dev 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 2mo 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/skill-dev/SKILL.md · 410 lines

The source is not reproduced here

No licence file

Read it on GitHub

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.

2mo ago First seen · 410 lines · 42 tokens per session scan A 57803110b947

Subscribe to this mod's changes

skill-dev is a skill published in the GitHub repository TimBeyer/agent-skills (2 stars, last pushed 7mo ago), with no licence file. It adds 42 tokens to every session and 3,356 once invoked, about $0.0002 per session on Opus 5.5. 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.

Building agents

skill-dev next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
skill-devTimBeyer/agent-skills	Skill	2	7mo ago	none	A	42	Claude Code, Codex
imagegenopenai/codex	Skill	134k	today	Apache-2.0	A	113	Codex
local-ai-agentsmicrosoft/ai-agents-for-beginners	Skill	79k	today	MIT	A	200	Claude Code, Codex
playwright-climicrosoft/playwright	Skill	99k	today	Apache-2.0	A	19	Claude Code
systematic-debuggingobra/superpowers	Skill	314k	3d ago	MIT	A	21	Claude Code
next-cache-components-adoptionvercel/next.js	Skill	143k	today	MIT	A	95	Claude Code
chat-pet-sprite-creationmicrosoft/vscode	Skill	195k	today	MIT	A	53	Claude Code, Codex