duck-adapt

duck-adapt is a skill for Claude Code from sprngr/rubber-duck. It costs 47 tokens per session (2,147 once invoked), scanned A, original, MIT.

A meta-skill for adapting external workflows or skills to a rubber-duck approach, which uses questions, evidence, and small approved changes to reason through work.

In plain words
What is it for?
Use it to adapt a skill, audit one for compliance and overlap, or decide whether a new skill should be added.
Why use it?
It helps check whether a proposed skill fits the project's working principles or unnecessarily overlaps with existing skills.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the rubber-duck plugin — 17 skills shipped together

Good fit Use it to adapt a skill, audit one for compliance and overlap, or decide whether a new skill should be added.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/sprngr/rubber-duck/duck-adapt
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 sprngr/rubber-duck --skill duck-adapt
Clone the repo
git clone --depth 1 https://github.com/sprngr/rubber-duck

Made for: Claude Code.

Or install rubber-duck, the plugin that ships this one along with the rest of its 17 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 duck-adapt

README.md
[![agentmods](https://agentmods.dev/badge/skills/sprngr/rubber-duck/duck-adapt/github.svg)](https://agentmods.dev/skills/sprngr/rubber-duck/duck-adapt)
Your own site
<a href="https://agentmods.dev/skills/sprngr/rubber-duck/duck-adapt"><img src="https://agentmods.dev/badge/skills/sprngr/rubber-duck/duck-adapt/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for duck-adapt

Your own site · 80×15
<a href="https://agentmods.dev/skills/sprngr/rubber-duck/duck-adapt"><img src="https://agentmods.dev/badge/skills/sprngr/rubber-duck/duck-adapt.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 47 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,147 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. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 1 finding, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium Excessive Agency · line 188
    Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.
    Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
How audits are shown
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 $0.00047 $0.02147
Opus 5 $0.00023 $0.01073
Sonnet 5 $0.00009 $0.00429
Haiku 4.5 $0.00005 $0.00215

Measured 10d ago against content hash ad78916dfd82, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

duck-adapt 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 10d 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/duck-adapt/SKILL.md · 307 lines

How it starts

The opening of the file, as written. The whole thing — 307 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Skill adapter 🦆. External skill -> duck philosophy.

Purpose

Transform external skills or workflows into rubber-duck-grounded versions that preserve intent while adding:

  • Socratic questioning flow
  • Evidence-first discipline
  • Duck Ladder minimal-change thinking
  • Execution approval gates
  • Prompt order standard compliance

Also validates existing duck-* skills and detects unnecessary duplication.

Philosophy Guardrails (skill-local)

Inherit shared guardrails from references/GUARDRAILS.md.

  • ask 1-3 targeted clarifying questions when context is incomplete
  • state assumptions explicitly when evidence is missing

Skill-specific delta:

  • Meta-skill: operates on skill definitions, not codebase directly
  • Output is skill draft, not implementation
  • Recommends skill rejection when overlap/duplication detected

Activation

Use when:

  • User provides external skill to adapt
  • User describes workflow/process to convert into skill
  • User asks to audit existing skill for philosophy compliance
  • User asks "should we add this skill" or "does this overlap"

Method

1. Intake and classification

Ask clarifying questions (up to 3) to establish:

For external skill adaptation:

  • Input format: full skill markdown, workflow doc, or concept description?
  • Intent: what problem does this skill solve?
  • Scope: mutating actions (edits/commands) or non-mutating (analysis/advice)?
  • Target audience: what context does user expect?

For skill audit:

  • Which skill to audit? (name or path)
  • Audit depth: quick compliance check or full overlap analysis?

For overlap detection:

  • Skill concept summary
  • Expected workflow steps
  • Comparison against existing skills requested?

2. Evidence gathering

For external skill:

  • Parse input: extract steps, constraints, outputs, examples
  • Identify decision points (where user choice matters)
  • Identify mutating actions (require approval gates)
  • Identify evidence gaps (where code/diff/log reading needed)

For skill audit:

Read the full file on GitHub · 307 lines

Files

What ships with it

7 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.

  1. 10d ago First seen · 307 lines · 47 tokens per session scan A ad78916dfd82

Subscribe to this mod's changes

duck-adapt is a skill published in the GitHub repository sprngr/rubber-duck (8 stars, last pushed today), licensed MIT. It adds 47 tokens to every session and 2,147 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.