skill-writer

A guide for creating and maintaining agent skills: instruction packages that teach an agent a repeatable workflow, domain knowledge, or how to use tools.

In plain words
What is it for?
Use it when writing or revising SKILL.md files, skill structure, activation triggers, workflows, scripts, references, or bundled assets.
Why use it?
It helps keep skills focused, consistent, and easy to activate without filling the agent's context with general programming advice.

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/crypticswarm/swarmforge/skill-writer
Any agent
npx skills add CrypticSwarm/Swarmforge --skill skill-writer
Clone the repo
git clone --depth 1 https://github.com/CrypticSwarm/Swarmforge

Made for: Claude Code, Codex.

Per session 47 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,755 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 $0.00047 $0.01755
Opus 5 $0.00023 $0.00877
Sonnet 5 $0.00009 $0.00351
Haiku 4.5 $0.00005 $0.00176

Measured 2d ago against content hash 3a6513031c50, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

skill-writer 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.

skills/skill-writer/SKILL.md · 117 lines

How it starts

The opening of the file, as written. The whole thing — 117 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Skill Writer

Use this guide whenever you need to create, revise, or maintain a skill (a modular package that expands the agent with domain knowledge, workflows, or tooling). Skills act like onboarding kits: they teach the agent how to approach a recurring problem reliably.

Skills at a Glance

  • Specialized workflows – codified, repeatable procedures for fragile or multi-step tasks.
  • Tool integrations – instructions for working with specific APIs, formats, or scripts.
  • Domain expertise – company, product, or dataset knowledge that the base model lacks.
  • Bundled resources – scripts, references, and assets reused across sessions.

Keep every skill lean. Assume the agent already knows general programming, writing, and reasoning; only include content that is unique to the domain or workflow.

Core Principles

  1. Implicit vs explicit activation.

    • Skills may be activated explicitly via the skill tool or implicitly via strong trigger language.
    • For fragile or critical workflows, assume explicit activation.
    • For common, narrow tasks (e.g. commit messages), optimize for implicit activation through the description.
  2. Protect the context window. Every token in a skill competes with live conversation history. Prefer short, actionable guidance over essays. Use tables, bullets, or concise examples instead of prose.

  3. Match specificity to task fragility.

    • High freedom → text instructions and heuristics (open problem spaces).
    • Medium freedom → pseudocode or parameterized scripts (preferred patterns, but variations allowed).
    • Low freedom → exact scripts/commands (fragile operations, compliance, or prod changes).
  4. Progressive disclosure. Organize content so only the necessary layer loads:

    1. YAML frontmatter (name, description) – always visible, describes when to trigger.
    2. SKILL.md body – core workflows (<500 lines).
    3. Optional scripts/, references/, assets/ – loaded only when invoked.

Read the full file on GitHub · 117 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. 2d ago First seen · 117 lines · 47 tokens per session scan A 3a6513031c50

Subscribe to this mod's changes

skill-writer is a skill published in the GitHub repository CrypticSwarm/Swarmforge (2 stars, last pushed 3d ago), licensed MIT. It adds 47 tokens to every session and 1,755 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 2026-08-31.

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