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.
npx skills add Grafuja/Product-Manager-Skills --skill experiment-designergit clone --depth 1 https://github.com/Grafuja/Product-Manager-SkillsWrote 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.
[](https://agentmods.dev/skills/grafuja/product-manager-skills/experiment-designer)<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.
<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>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 | $0.00091 | $0.04232 |
| Opus 5 | $0.00046 | $0.02116 |
| Sonnet 5 | $0.00018 | $0.00846 |
| Haiku 4.5 | $0.00009 | $0.00423 |
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.
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 |
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.
- 11d ago First seen · 690 lines · 91 tokens per session scan A 7d9bf5b7a3d2
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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