experiment-designer

experiment-designer is a skill for Claude Code, Codex from Grafuja/Product-Manager-Skills. It costs 91 tokens per session (4,232 once invoked), scanned A, original, MIT.

A guide for testing whether a proposed product feature is worth building before committing to full development. It turns an uncertain idea into a hypothesis and a small validation test.

In plain words
What is it for?
Use it to define an if-then hypothesis, choose a lightweight prototype or research test, set measurable success criteria, and decide whether the evidence supports building the feature.
Why use it?
It reduces the risk of spending weeks building a feature that users do not need or would not use.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: positional $N argument.

Good fit Use it to define an if-then hypothesis, choose a lightweight prototype or research test, set measurable success criteria, and decide whether the evidence supports building the feature.

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Install with agentmods
npx agentmods add skills/grafuja/product-manager-skills/experiment-designer
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 Grafuja/Product-Manager-Skills --skill experiment-designer
Clone the repo
git clone --depth 1 https://github.com/Grafuja/Product-Manager-Skills

Made for: Claude Code, Codex.

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 experiment-designer

README.md
[![agentmods](https://agentmods.dev/badge/skills/grafuja/product-manager-skills/experiment-designer/github.svg)](https://agentmods.dev/skills/grafuja/product-manager-skills/experiment-designer)
Your own site
<a href="https://agentmods.dev/skills/grafuja/product-manager-skills/experiment-designer"><img src="https://agentmods.dev/badge/skills/grafuja/product-manager-skills/experiment-designer/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 experiment-designer

Your own site · 80×15
<a href="https://agentmods.dev/skills/grafuja/product-manager-skills/experiment-designer"><img src="https://agentmods.dev/badge/skills/grafuja/product-manager-skills/experiment-designer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 91 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,232 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 $0.00091 $0.04232
Opus 5 $0.00046 $0.02116
Sonnet 5 $0.00018 $0.00846
Haiku 4.5 $0.00009 $0.00423

Measured 11d ago against content hash 7d9bf5b7a3d2, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

experiment-designer 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 11d 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/experiment-designer/SKILL.md · 690 lines

How it starts

The opening of the file, as written. The whole thing — 690 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Experiment Designer

Help product managers design lightweight validation experiments to test hypotheses before committing to full development.

Core Philosophy

Don't build to learn. Experiment to learn, then build.

Experiments answer: "Should we build this?" before investing weeks/months.


When to Use This Skill

Trigger experiment design when:

  • Confidence < 70% on an initiative
  • User asks "should we build X?"
  • Feature is expensive (>4 weeks effort)
  • Stakeholder request without user validation
  • New product/market with uncertainty

Don't experiment when:

  • Obvious must-have (e.g., fix critical bug)
  • Feature already validated
  • Regulatory requirement
  • Confidence > 80% with solid data

The Experiment Design Workflow

Step 1: Capture the Hypothesis

Ask: "What do you believe to be true that you want to test?"

Help them form a clear hypothesis in IF-THEN format:

Template:

IF [we do X action],
THEN [Y measurable result will happen]
BECAUSE [assumption about users]

Examples:

Good hypothesis: "IF we show dashboard prototype to 10 CFOs, THEN 8/10 will say they'd use it weekly BECAUSE CFOs waste 30min/week on manual reports"

Bad hypothesis (too vague): "IF we build dashboard, THEN users will like it"

Push for specificity:

  • What EXACTLY are we testing?
  • What EXACT result would confirm it?
  • What's the underlying assumption?

Store: hypothesis (IF-THEN-BECAUSE statement)


Step 2: Assess Current Confidence

Ask: "How confident are you (0-100%) that this will work?"

This determines which experiment method to use:

Confidence What it means Experiment needed
0-30% Pure speculation Heavy validation (interviews, prototype)
30-50% Weak signal Moderate validation (wizard of oz, concierge)
50-70% Some evidence Light validation (feature flags, beta)
70-100% Strong evidence Minimal/no experiment, just build

Read the full file on GitHub · 690 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. 11d ago First seen · 690 lines · 91 tokens per session scan A 7d9bf5b7a3d2

Subscribe to this mod's changes

experiment-designer is a skill published in the GitHub repository Grafuja/Product-Manager-Skills (9 stars, last pushed 5mo ago), licensed MIT. It adds 91 tokens to every session and 4,232 once invoked, about $0.0005 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.

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