What is skill-writer?

A skill for creating and improving agent skills, which are instruction packages that teach an agent how to handle a particular kind of work. It follows the Agent Skills specification.

Use it to create, synthesize, improve, update, or maintain agent skills and their registration documentation.

It helps organize skill instructions and refine them over time instead of writing undocumented prompts from scratch. The input does not describe its exact output files or workflow.

skill-writer — Skill by getsentry

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/getsentry/warden/skill-writer

Any agent

npx skills add getsentry/warden --skill skill-writer

Clone the repo

git clone --depth 1 https://github.com/getsentry/warden

Made for: Claude Code, Codex.

Per session 83 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 2,070 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. Scan, not verified.

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	$0.00083	$0.02070
Opus 5	$0.00042	$0.01035
Sonnet 5	$0.00017	$0.00414
Haiku 4.5	$0.00008	$0.00207

Measured 3d ago against content hash dcada5aeeac2, 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 3d ago.

The scan reads SKILL.md. This mod also ships 2 executable files (scripts/quick_validate_test.py, scripts/quick_validate.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

packages/warden/src/internal-skills/skill-writer/SKILL.md · 160 lines

The source is not reproduced here

No licence file

Read it on GitHub

Files

What ships with it

44 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.

3d ago First seen · 160 lines · 83 tokens per session scan A dcada5aeeac2

Subscribe to this mod's changes

skill-writer is a skill published in the GitHub repository getsentry/warden (403 stars, last pushed 4d ago), with no licence file. It adds 83 tokens to every session and 2,070 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 2026-08-30.

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