skill-author

skill-author is an agent for Claude Code from GuitarAlchemist/ga. It costs 70 tokens per session (1,149 once invoked), scanned A, original, MIT.

A drafting agent that creates a new SKILL.md file, which is an instruction file for a chatbot capability, from a description of the intended behaviour.

In plain words
What is it for?
Use it to start catalog, computation, or hybrid chatbot skills, with an optional list of example prompts and a classification.
Why use it?
It gives a new skill the required structure and checks its name and inputs before development continues.

Agent for Claude Code

Written for Claude Code: installed under .claude/. Also seen: mentions Claude Code.

Good fit Use it to start catalog, computation, or hybrid chatbot skills, with an optional list of example prompts and a classification.

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Install with agentmods
npx agentmods add agents/guitaralchemist/ga/skill-author
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.

Clone the repo
git clone --depth 1 https://github.com/GuitarAlchemist/ga

Made for: Claude Code.

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-author

README.md
[![agentmods](https://agentmods.dev/badge/agents/guitaralchemist/ga/skill-author/github.svg)](https://agentmods.dev/agents/guitaralchemist/ga/skill-author)
Your own site
<a href="https://agentmods.dev/agents/guitaralchemist/ga/skill-author"><img src="https://agentmods.dev/badge/agents/guitaralchemist/ga/skill-author/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 skill-author

Your own site · 80×15
<a href="https://agentmods.dev/agents/guitaralchemist/ga/skill-author"><img src="https://agentmods.dev/badge/agents/guitaralchemist/ga/skill-author.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 70 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,149 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 $0.00070 $0.01149
Opus 5.5 $0.00028 $0.00460
Sonnet 5.5 $0.00014 $0.00230
Haiku 4.5 $0.00007 $0.00115

Measured 2mo ago against content hash 87e35fa55a2d, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

skill-author 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.

.claude/agents/skill-author.md · 123 lines

How it starts

The opening of the file, as written. The whole thing — 123 lines — stays where its author put it; the contents beside it link to each section on GitHub.

skill-author — draft a new chatbot skill

Generate a fresh SKILL.md under skills-dev/<name>/ so the user can start iterating immediately. The output must satisfy GA's SKILL.md schema so the chatbot's FileBasedSkillsProvider picks it up via live-reload, and Claude Code can also load it as a plugin skill.

Inputs the user provides

  • A short name (kebab-case, like progression-mood or chord-info).
  • A one-paragraph description of what the skill should do.
  • Optional: example user prompts that should trigger it.
  • Optional: classification — catalog (deterministic lookup, no LLM per call), computation (calls an MCP tool deterministically), or hybrid (LLM synthesizes over a deterministic substrate).

Pre-flight checks (refuse if these fail)

  1. No name collision: glob skills/<name>/SKILL.md and skills-dev/<name>/SKILL.md. If either exists, refuse and tell the user to either pick a different name OR explicitly invoke the graduator/redrafter pattern (move existing to drafts first).
  2. Name is kebab-case: ^[a-z][a-z0-9-]*$. Reject snake_case, PascalCase, spaces.
  3. Description is non-empty and contains at least one usage hint like "use when" or "when the user asks". The description is what the orchestrator's intent router (and Claude Code's slash-command matcher) score against — vague descriptions misroute.

Output template

---
name: <name>
description: |
  <one paragraph: what the skill returns, when to use it, what
   evidence kind it produces. Include 2-3 user-prompt fragments
   the orchestrator should match against.>
triggers:
  - "<trigger phrase 1>"
  - "<trigger phrase 2>"
  - "<trigger phrase 3>"
license: internal
compatibility:
  agent-framework: ">=1.0.0-preview"
metadata:
  authoring-style: <deterministic-catalog | mcp-tool-driven | hybrid-llm>
  origin: "drafted by skill-author agent on <ISO date>"
  evidence-kinds:
    - <catalog_lookup | mcp_tool_call | llm_synthesis>
---

# <Skill title>

## When the chatbot dispatches to this skill

<Concrete user-prompt examples — at least 3. The orchestrator's intent
router compares user messages against THIS body as well as the
description, so concrete examples here improve routing precision.>

## What the skill returns

<Output structure: sections, fields, formats. Include a short example
output if the format is non-obvious.>

## How the skill computes

<Reference the implementation: an `IOrchestratorSkill` class for
catalog skills, an MCP tool name for tool-driven skills, or "LLM
synthesis grounded on <X>" for hybrid skills. State whether the
behaviour is fully deterministic or whether the LLM is in the path.>

## Refuse to invent

<List the things the skill MUST NOT hallucinate — chord voicings
outside the catalog, scale memberships, set-class numbers, etc. The
chatbot's groundedness validator gates on these.>

Read the full file on GitHub · 123 lines

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. 2mo ago First seen · 123 lines · 70 tokens per session scan A 87e35fa55a2d

Subscribe to this mod's changes

skill-author is an agent published in the GitHub repository GuitarAlchemist/ga (2 stars, last pushed yesterday), licensed MIT. It adds 70 tokens to every session and 1,149 once invoked, about $0.0003 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.

Related

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