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.
npx agentmods add skills/oleg494/coding-kit/skill-authoringnpx skills add oleg494/coding-kit --skill skill-authoringgit clone --depth 1 https://github.com/oleg494/coding-kitWhat 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 | $0.00093 | $0.01247 |
| Opus 5 | $0.00046 | $0.00624 |
| Sonnet 5 | $0.00019 | $0.00249 |
| Haiku 4.5 | $0.00009 | $0.00125 |
Grade B, and why
skill-authoring scanned grade B with 1 finding 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.
Enumerates other installed skillsmediumAgent snooping
Other skills' SKILL.md files reveal prompts, capabilities and secrets that should be invisible to peers.
4. **Choose the location.** Portable (any machine/project) → kit `skills/<slug>/`, commit — subject to the kit gates (English, file-size, review), propagates to every harness automatically. Machine/user-specific → the ha How it starts
The opening of the file, as written. The whole thing — 96 lines — stays where its author put it; the contents beside it link to each section on GitHub.
How to author skills correctly
A set of rules based on the Agent Skills specification + practice. Verified against real skills.
1. Frontmatter (required fields)
---
name: my-skill
description: Use when [triggers/symptoms/contexts]. [what it does + when to apply]
---
| Field | Rule |
|---|---|
name |
REQUIRED. 1–64 characters, a-z0-9 + hyphens. Must match the skill's folder name |
description |
REQUIRED. 1–1024 characters. «What it does + when to use»; include the keywords the agent searches by. NOT a workflow summary |
license |
optional |
compatibility |
1–500 characters, only if there are environment requirements |
2. Directory structure
skill-name/
├── SKILL.md # required
├── scripts/ # optional: executable scripts
├── references/ # optional: details, «read when X»
├── assets/ # optional
└── any other files/folders — allowed
- From SKILL.md reference files with relative paths from the skill root.
- Progressive disclosure: SKILL.md < ~500 lines; details go into
references/with a pointer «read this when X happens».
3. Script bundling (scripts/)
- First check for an existing tool:
npx,uvx,pipx,bunx— take an existing one, write your own only when none exists. - If you bundle a script, it must be self-contained: document dependencies in SKILL.md or
compatibility. - Agent-safe design:
- NO interactive prompts — the agent will hang on a TTY. Input only via arguments.
--helpwith usage; clear error messages.- Structured output: result to stdout, diagnostics to stderr.
- Idempotency;
--dry-runfor destructive operations. - Predictable output size (agents truncate ~10–30K characters).
4. Best practices and antipatterns
Do:
- Small, composable, like a function: one coherent task.
- Description in the imperative: «Use when …», list the triggers. Agents under-trigger.
- Add what the agent does not know; drop what it already can do.
Gotchassections — the most valuable content; checklists for multi-step processes; output templates.- Defaults, not menus; procedures, not declarations; explain «why».
- Calibrate detail to fragility: for fragile operations — prescriptively.
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.
- 2d ago First seen · 96 lines · 93 tokens per session scan B 2ae9015cebfc
skill-authoring is a skill published in the GitHub repository oleg494/coding-kit (1 stars, last pushed 2d ago), licensed MIT. It adds 93 tokens to every session and 1,247 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it B with 1 finding (enumerates other installed skills). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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