agent-skill-authoring

agent-skill-authoring is a skill for Claude Code from bdfinst/agentic-dev-team. It costs 75 tokens per session (1,588 once invoked), scanned A, original, MIT.

A writing guide for creating and editing SKILL.md files, which store reusable instructions for coding agents. It explains how skills should differ from agents and how they should be documented and registered.

In plain words
What is it for?
Use it when creating, editing, or reviewing a skill, especially when deciding whether content belongs in an agent or a skill.
Why use it?
It prevents workflow decisions from being mixed with step-by-step knowledge, duplicated across files, or left out of the plugin's registration records.

Skill for Claude Code

Written for Claude Code: user-invocable in frontmatter. Also seen: mentions CLAUDE.md.

Part of the marketplace-dev plugin — 10 skills, 1 agent shipped together

Good fit Use it when creating, editing, or reviewing a skill, especially when deciding whether content belongs in an agent or a skill.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/bdfinst/agentic-dev-team/agent-skill-authoring
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 bdfinst/agentic-dev-team --skill agent-skill-authoring
Clone the repo
git clone --depth 1 https://github.com/bdfinst/agentic-dev-team

Made for: Claude Code.

Or install marketplace-dev, the plugin that ships this one along with the rest of its 10 skills, 1 agent.

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 agent-skill-authoring

README.md
[![agentmods](https://agentmods.dev/badge/skills/bdfinst/agentic-dev-team/agent-skill-authoring.svg)](https://agentmods.dev/skills/bdfinst/agentic-dev-team/agent-skill-authoring)
Your own site
<a href="https://agentmods.dev/skills/bdfinst/agentic-dev-team/agent-skill-authoring"><img src="https://agentmods.dev/badge/skills/bdfinst/agentic-dev-team/agent-skill-authoring.svg" alt="Measured on agentmods" height="20"></a>
Per session 75 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,588 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 $0.00075 $0.01588
Opus 5 $0.00037 $0.00794
Sonnet 5 $0.00015 $0.00318
Haiku 4.5 $0.00007 $0.00159

Measured 2d ago against content hash db4b69ea99b9, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

agent-skill-authoring 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 2d 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.

plugins/marketplace-dev/skills/agent-skill-authoring/SKILL.md · 109 lines

How it starts

The opening of the file, as written. The whole thing — 109 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Agent & Skill Authoring

Overview

This skill defines the philosophy of the agent-vs-skill split and the conventions for writing skills. Agents own orchestration logic (when and why); skills own execution knowledge (how). This separation keeps agents readable as workflow definitions while keeping capabilities DRY across the team.

Scope boundary:

  • This skill — skill creation, shared philosophy, anti-patterns, documentation sync policy
  • agent-create skill — the procedural workflow for generating a new agent file (invoked by /agent-add)

If you are creating an agent file, use /agent-add (which invokes the agent-create skill). This skill no longer duplicates that procedure.

Constraints

  • Skills must be agent-agnostic; no persona or behavioral logic in skill files
  • Execution details belong in skills; orchestration logic belongs in agents
  • Every new agent or skill must be registered (see references/templates.md)
  • Do not embed a skill's knowledge inline in an agent — reference the skill file

Core Pattern

Agent (when + why)          Skill (how)
┌─────────────────┐        ┌─────────────────┐
│ ## Skills        │        │ # Skill Name    │
│ - Skill A ──────│───────>│                 │
│   "Invoke when  │        │ ## Concepts     │
│    designing    │        │ ## Patterns     │
│    bounded      │        │ ## Guidelines   │
│    contexts"    │        │ ## Structure    │
│                 │        │                 │
│ ## Behavioral   │        │ (reusable by    │
│   Guidelines    │        │  any agent)     │
│ (orchestration) │        │                 │
└─────────────────┘        └─────────────────┘
  • Agents define the role: persona, behavior, collaboration style, and when/why to use each skill
  • Skills define the capability: concepts, patterns, guidelines, and project structures
  • An agent references a skill and annotates it with invocation context
  • Multiple agents can share the same skill, each with different invocation context

Read the full file on GitHub · 109 lines

Files

What ships with it

1 file 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. 2d ago First seen · 109 lines · 75 tokens per session scan A db4b69ea99b9

Subscribe to this mod's changes

agent-skill-authoring is a skill published in the GitHub repository bdfinst/agentic-dev-team (280 stars, last pushed 2d ago), licensed MIT. It adds 75 tokens to every session and 1,588 once invoked, about $0.0004 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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