identify-assumptions-existing

identify-assumptions-existing is a skill for Claude Code from yuusakuri/agent-skills. It costs 58 tokens per session (466 once invoked), scanned A, a copy of identify-assumptions-existing, MIT.

A structured review method for finding risky assumptions behind a feature idea in an existing product.

In plain words
What is it for?
It uses product, design, and engineering viewpoints to assess assumptions across value, usability, viability, and feasibility.
Why use it?
It exposes ways a feature could fail before implementation, including problems with customer value, usability, business support, or technical feasibility.

Skill for Claude Code

Written for Claude Code: $ARGUMENTS substitution.

Good fit It uses product, design, and engineering viewpoints to assess assumptions across value, usability, viability, and feasibility.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/yuusakuri/agent-skills/identify-assumptions-existing
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 yuusakuri/agent-skills --skill identify-assumptions-existing
Clone the repo
git clone --depth 1 https://github.com/yuusakuri/agent-skills

Made for: Claude Code.

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 identify-assumptions-existing

README.md
[![agentmods](https://agentmods.dev/badge/skills/yuusakuri/agent-skills/identify-assumptions-existing/github.svg)](https://agentmods.dev/skills/yuusakuri/agent-skills/identify-assumptions-existing)
Your own site
<a href="https://agentmods.dev/skills/yuusakuri/agent-skills/identify-assumptions-existing"><img src="https://agentmods.dev/badge/skills/yuusakuri/agent-skills/identify-assumptions-existing/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 identify-assumptions-existing

Your own site · 80×15
<a href="https://agentmods.dev/skills/yuusakuri/agent-skills/identify-assumptions-existing"><img src="https://agentmods.dev/badge/skills/yuusakuri/agent-skills/identify-assumptions-existing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 58 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 466 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 100% copy Near-identical to another mod 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 $0.00058 $0.00466
Opus 5.5 $0.00023 $0.00186
Sonnet 5.5 $0.00012 $0.00093
Haiku 4.5 $0.00006 $0.00047

Measured 2mo ago against content hash 59d788213014, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

identify-assumptions-existing 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 2mo 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.

Origin

This is a copy

100% identical to identify-assumptions-existing — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/identify-assumptions-existing/SKILL.md · 45 lines

What it actually says

Identify Assumptions (Existing Product)

Devil's advocate analysis to surface risky assumptions across four risk areas.

Context

You are stress-testing a feature idea for $ARGUMENTS.

If the user provides files (designs, PRDs, research), read them first.

Instructions

The user will describe their product, objective, market segment, and feature idea. Work through these steps:

  1. Think from three perspectives about why this feature might fail:

    • Product Manager perspective: Business viability, market fit, strategic alignment
    • Designer perspective: Usability, user experience, adoption barriers
    • Engineer perspective: Technical feasibility, performance, integration challenges
  2. Identify assumptions across four risk areas:

    • Value: Will it create value for customers? Does it solve a real problem?
    • Usability: Will users figure out how to use it? Is the learning curve acceptable?
    • Viability: Can marketing, sales, finance, and legal support it?
    • Feasibility: Can it be built with existing technology? Are there integration risks?
  3. For each assumption, note:

    • What specifically could go wrong
    • How confident you are (High/Medium/Low)
    • Suggested way to test it

Think step by step. Be thorough but constructive — the goal is to strengthen the idea, not kill it.


Further Reading

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. 2mo ago First seen · 45 lines · 58 tokens per session scan A 59d788213014

Subscribe to this mod's changes

identify-assumptions-existing is a skill published in the GitHub repository yuusakuri/agent-skills (2 stars, last pushed 14d ago), licensed MIT. It adds 58 tokens to every session and 466 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 100% identical to identify-assumptions-existing, differing in 0 lines, and is treated as a copy.

Related

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