chisel

A skill that rewrites a vague prompt into an executable specification with requirements that can be observed, measured, or scored. It records how ambiguous terms, conflicting instructions, and intentionally open choices were handled.

In plain words
What is it for?
Use it to turn prompts into concrete acceptance criteria, numeric limits, observable behaviors, and a traceable decision record.
Why use it?
It reduces disagreement about what a prompt means and makes the expected result easier to check. It is useful when words such as “high quality,” “clear,” or “powerful” leave too much open to interpretation.

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/simota/agent-skills/chisel
Any agent
npx skills add simota/agent-skills --skill chisel
Clone the repo
git clone --depth 1 https://github.com/simota/agent-skills

Made for: Claude Code, Codex.

Per session 115 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,457 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 $0.00115 $0.05457
Opus 5 $0.00057 $0.02729
Sonnet 5 $0.00023 $0.01091
Haiku 4.5 $0.00012 $0.00546

Measured 2d ago against content hash 4e82a48c86d0, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

chisel 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.

chisel/SKILL.md · 277 lines

How it starts

The opening of the file, as written. The whole thing — 277 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Chisel

"A vague word is a decision you left to chance. Carve it into something that can be checked."

Take a prompt as it was written and return it as an executable specification: every expression that admits two defensible readings is either replaced with a bound, a behavior, or a scorable criterion, or is deliberately left open with a recorded reason. Chisel changes the language, never the intent — the source's goal, audience, and constraints are invariants.

Principles: Traceable over fluent · Observable over descriptive · Licensed numbers over invented ones · Capability over title · Open on purpose, never by accident

Read the full file on GitHub · 277 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 · 277 lines · 115 tokens per session scan A 4e82a48c86d0

Subscribe to this mod's changes

chisel is a skill published in the GitHub repository simota/agent-skills (75 stars, last pushed 8d ago), licensed MIT. It adds 115 tokens to every session and 5,457 once invoked, about $0.0006 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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