A routing helper for Rubber Duck workflows, where you explain a problem aloud or in writing to clarify your thinking and find the right next step.

Invoke it with “quack” to route a workflow request or select a specific helper. Invoke bare “quack” for its heartbeat and quick-help response.

It gives you a controlled way to route a request instead of relying on an automatic guess. It can ask a focused question when your request is unclear.

quack — Skill for Claude Code by sprngr

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 quack

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/sprngr/rubber-duck/quack/github.svg)](https://agentmods.dev/skills/sprngr/rubber-duck/quack)

Your own site

<a href="https://agentmods.dev/skills/sprngr/rubber-duck/quack"><img src="https://agentmods.dev/badge/skills/sprngr/rubber-duck/quack/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/sprngr/rubber-duck/quack"><img src="https://agentmods.dev/badge/skills/sprngr/rubber-duck/quack.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 28 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,241 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.

Model	Per session	Once invoked
Fable 5.1	$0.00028	$0.01241
Opus 5	$0.00014	$0.00620
Sonnet 5	$0.00006	$0.00248
Haiku 4.5	$0.00003	$0.00124

Measured 8d ago against content hash 96b3ed6e1bb7, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

quack 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 8d 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/quack/SKILL.md · 87 lines

How it starts

The opening of the file, as written. The whole thing — 87 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Skill: quack

Explicit route control 🦆. Alias-first auto-route, else one targeted disambiguation question.

Purpose

Provide explicit user-controlled routing for workflow-like requests while preserving safety and approval constraints.

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

Activation

Use only when user explicitly invokes quack; do not auto-activate from inferred intent.

Method

Verify explicit quack invocation.
Normalize intent: strip separator after quack (:, -, —), strip outer matching quotes, strip trailing punctuation (?!.;:).
Bare quack (heartbeat path):
- If normalized intent is empty or whitespace-only:
  - Read assets/heartbeat.md and select one random heartbeat line from the list
  - Read and emit full assets/quick-help.md content verbatim (no summarization)
  - Emit closing prompt: What would you like to route?
  - Stop (do not generate ad-hoc quips, do not enter disambiguation)
Parse optional override: use <subagent> or with <subagent> or via <subagent>.
Validate override (if present) against platform subagent list; if invalid, ask one correction question: Need one detail: unknown subagent "<x>". Use duckling or general? and stop.
Determine effective subagent: if override parsed in step 4, use that; otherwise default to duckling.
Determine route execution policy:
- inline-default: duck-design, duck-teach, duck-debug, duck-debt
- delegated-default: duck-patch, duck-refactor, duck-risk, duck-review, duck-triage, duck-simplify
- user override forces delegation regardless of default policy
If explicit full skill name in input, resolve that skill and execute route (see step 11).
Otherwise, load assets/route-aliases.json and attempt case-insensitive match.
Apply keyword-based precedence (when multiple skills match):
- Scan intent for precedence keywords:
  - Risk signals (rollback, breaking, compatibility, compat, failure, impact) -> prioritize duck-risk
  - Complexity signals (overengineered, complexity, simpler, too many, bloated) -> prioritize duck-simplify
  - Learning signals (why, how, what does, explain, teach me) -> prioritize duck-teach over duck-debug
  - Test signals (test, coverage, should I test, before PR) -> prioritize duck-triage
  - Design signals (choose, tradeoff, approach, option) -> prioritize duck-design
- Reorder matched skills with precedence-matched skill first
- Still present alternatives (precedence aids ranking, doesn't eliminate choice)
If multiple aliases match after precedence, apply tie-break: exact match > longest alias > ask one disambiguation question.
Route execution (explicit skill name or alias match):
- Load role instructions from assets/subagent-runbook.md for resolved skill
- If inline-default policy AND no user override:
  - execute skill inline first
  - if execution fails, ask one corrective question and stop
  - emit Routing: <skill>. only after inline execution step completes
- Otherwise (delegated-default OR user override):
  - delegate to subagent using harness-native dispatch tool with subagent=<effective_subagent> (determined in step 6, defaults to duckling) first
  - pass skill_name=<resolved_skill> parameter
  - if dispatch fails, ask one corrective question and stop
  - emit Routing: <skill> via <subagent>. if user override supplied, else Routing: <skill>. only after dispatch succeeds
- Do not stop at routing text alone when execution path is available.
Alias miss (disambiguation):
- Detect intent fragment and ask one targeted question:
  - debug-ish (error/fail/trace/stack/broken): Need one detail: is this debug, trace, or review?
  - rollout/risk (rollout/migration/compat/rollback): Need one detail: is this risk review or design tradeoff?
  - code-change (fix/change/refactor/clean up): Need one detail: do you want review, patch, refactor, or simplify?
  - tech-debt (todo/defer/fixme/debt): Need one detail: is this debt audit or simplify?
  - unknown: Need one detail: which route fits—review, debug, design, teach, triage, risk, simplify, patch, refactor, or debt?
- Wait for user clarification, then retry alias resolution.

Read the full file on GitHub · 87 lines

Files

What ships with it

6 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.

8d ago First seen · 87 lines · 28 tokens per session scan A 96b3ed6e1bb7

Subscribe to this mod's changes

quack is a skill published in the GitHub repository sprngr/rubber-duck (8 stars, last pushed 4d ago), licensed MIT. It adds 28 tokens to every session and 1,241 once invoked, about $0.0001 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.

Claude Code Planning agent-skills ai-agents antivibe decision-quality developer-tools

expert-redteam-review

Use when a user asks to evaluate a complex, high-impact, ambiguous, cross-functional, or hard-to-reverse decision; mentions expert panel, red team, adversarial review, rebuttal, judge, arbitration, risk review, challenge assumptions, poke holes, or wants stronger decision quality than a normal review.

carbonshow/intent-fluid · 67 tokens

quack

Getting it into your agent

Wrote this? Show the measurements

What it costs to keep this loaded

Grade A, and why

Nothing flagged

How it starts

Skill: quack

Purpose

Philosophy Guardrails (skill-local)

Activation

Method

What ships with it

What this file has done since we first saw it

Other skills, from other repositories

expert-redteam-review

haiku

rework-rate

taiyi-ui-design

ln-62-repository-publisher

remove