anvil

anvil is a skill for Claude Code from takubii/smithy. It costs 60 tokens per session (1,300 once invoked), scanned A, original, MIT.

A workflow coordinator for software tasks that keeps plans, decisions, implementation notes, reviews, and verification results in durable local task files. It organizes work into research, clarification, implementation, review, and verification stages.

In plain words
What is it for?
Use it when invoking Smithy or Anvil, starting or resuming a tracked task, or running the full plan-to-verified-result workflow.
Why use it?
It prevents important task context and decisions from being lost between steps or sessions.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: names the AskUserQuestion tool.

Part of the smithy plugin — 4 skills shipped together

Good fit Use it when invoking Smithy or Anvil, starting or resuming a tracked task, or running the full plan-to-verified-result workflow.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/takubii/smithy/anvil
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.

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

Made for: Claude Code.

Or install smithy, the plugin that ships this one along with the rest of its 4 skills.

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 anvil

README.md
[![agentmods](https://agentmods.dev/badge/skills/takubii/smithy/anvil.svg)](https://agentmods.dev/skills/takubii/smithy/anvil)
Your own site
<a href="https://agentmods.dev/skills/takubii/smithy/anvil"><img src="https://agentmods.dev/badge/skills/takubii/smithy/anvil.svg" alt="Measured on agentmods" height="20"></a>
Per session 60 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,300 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 $0.00060 $0.01300
Opus 5 $0.00030 $0.00650
Sonnet 5 $0.00012 $0.00260
Haiku 4.5 $0.00006 $0.00130

Measured 7d ago against content hash d0e5fce91783, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

anvil 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 7d 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-code/plugins/smithy/skills/anvil/SKILL.md · 120 lines

How it starts

The opening of the file, as written. The whole thing — 120 lines — stays where its author put it; the contents beside it link to each section on GitHub.

anvil

Manage task state and orchestrate the workflow. This is the only skill that knows the .smithy/tasks/ storage format.

Use the workflow skills for focused phases:

  • Use forge to produce research, plan, todos, and verification guidance.
  • Use quench to produce design questions and decisions.
  • Use polish to produce independent review findings and convergence advice.

Record their results in the Smithy task file.

Core rule

Keep the user involved for product/design decisions and final approval. Do not ask the user to choose routine implementation mechanics when the codebase gives a clear answer. Escalate only when scope, acceptance criteria, risk, or non-goals change.

Implementation handoff

After the user approves the plan, delegate implementation with Task when the tool is available. Give the implementer only the execution context it needs:

  • User intent.
  • Acceptance criteria.
  • Non-goals.
  • Approved plan and decisions.
  • Implementation todos.
  • Relevant files, commands, and constraints.
  • Verification expectations.

The implementer owns code changes for the approved scope and reports any verification it ran. anvil still owns Smithy task state, user-facing decisions, verification recording, review adjudication, and final approval. If Task is unavailable, implement directly while preserving the same boundaries.

Task state updates

Treat each Smithy task file as one document with two different zones:

  • Current sections are authoritative working state. Keep them concise, current, and free of superseded plans, completed todos, rejected options, and stale assumptions.
  • History sections are non-authoritative audit state. Append important decisions, progress, review outcomes, and superseded notes there so the reasoning remains available without polluting normal working context.

Update rules:

  • Rewrite current sections when the active plan, todos, verification state, or open questions change.
  • Remove completed todos and obsolete options from current sections.
  • Append meaningful reasons for changes to the relevant history log.
  • Move old but still useful information to superseded notes with what replaced it and why.
  • Fix typos, broken links, and obvious recording errors in place.
  • Update Last updated whenever the task file changes.

Read the full file on GitHub · 120 lines

Files

What ships with it

1 file 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.

  1. 7d ago First seen · 120 lines · 60 tokens per session scan A d0e5fce91783

Subscribe to this mod's changes

anvil is a skill published in the GitHub repository takubii/smithy (2 stars, last pushed 2mo ago), licensed MIT. It adds 60 tokens to every session and 1,300 once invoked, about $0.0003 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.