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Agent skill

Brainstorm Experiments Existing

by phuryn in phuryn/pm-skills

Design experiments to test assumptions for an existing product — prototypes, A/B tests, spikes, and other low-effort validation methods.

MITAuto-check passedAgent Workflows

Install Brainstorm Experiments Existing

skills CLI
$ npx skills add phuryn/pm-skills --skill brainstorm-experiments-existing -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install phuryn/pm-skills brainstorm-experiments-existing --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/phuryn/pm-skills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/pm-product-discovery/skills/brainstorm-experiments-existing .claude/skills/brainstorm-experiments-existing && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
brainstorm-experiments-existing
GitHub stars
27k
Token cost
~601 tokens
SKILL.md length
249 words
Files
1
Skills in repo
67
Repo updated
First seen
Licence
MIT

At a glance

Design experiments to test assumptions for an existing product — prototypes, A/B tests, spikes, and other low-effort validation methods.

  • Works in 4 steps: Clarify the idea and assumptions:… → Suggest experiments for each assumption.… → Key principles to follow → …
  • Validating assumptions
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
  • Testing feature ideas cheaply

What it does

Brainstorm Experiments Existing is an agent skill from phuryn/pm-skills. Design experiments to test assumptions for an existing product — prototypes, A/B tests, spikes, and other low-effort validation methods. Use when validating assumptions, testing feature ideas cheaply, or planning product experiments.

Its SKILL.md is about 600 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Agent Workflows, covering Brainstorming and A/B testing. The repository describes itself as: PM Skills Marketplace: 100+ agentic skills, commands, and plugins — from discovery to strategy, execution, launch, and growth. The licence is MIT.

When your agent uses it

  • Validating assumptions
  • Testing feature ideas cheaply
  • Planning product experiments

Example prompts

  • “/brainstorm-experiments-existing”

Workflow steps

4 steps, taken from the first numbered list in SKILL.md.

  1. Clarify the idea and assumptions: Confirm what the team wants to build and what they need to validate.
  2. Suggest experiments for each assumption. Consider methods like
  3. Key principles to follow
  4. For each experiment, specify

What it can do on your machine

Read from SKILL.md and the folder at commit 8607e3b. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md.

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    Links to these hosts (documentation or services it may open):

    • productcompass.pm

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Brainstorm Experiments Existing loads about 601 tokens when it runs. Until then it costs about 66 tokens; SKILL.md has 249 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~66
When it runs · the whole SKILL.md, loaded when a task matches
~601

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from phuryn/pm-skills at commit 8607e3b, republished under its MIT licence (© phuryn). 249 words, ~601 tokens.

Download SKILL.mdSave it as .claude/skills/brainstorm-experiments-existing/SKILL.md (or your agent's skills folder).
name
brainstorm-experiments-existing
description
Design experiments to test assumptions for an existing product — prototypes, A/B tests, spikes, and other low-effort validation methods. Use when validating assumptions, testing feature ideas cheaply, or planning product experiments.

Design Experiments (Existing Product)

Design low-effort experiments to test product assumptions before committing to full implementation.

Context

You are helping a product team design experiments for $ARGUMENTS. The team has a feature idea and assumptions that need validation.

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

Instructions

The user will describe their idea and assumptions. Work through these steps:

  1. Clarify the idea and assumptions: Confirm what the team wants to build and what they need to validate.

  2. Suggest experiments for each assumption. Consider methods like:

    • First-click testing or task completion with a prototype
    • Feature stubs or fake door tests
    • Technical spikes
    • A/B tests on production (with risk mitigation)
    • Wizard of Oz approaches
    • Survey-based validation (behavioral, not opinion-based)

  3. Key principles to follow:

    • Measure actual behavior, not users' opinions
    • Test responsibly — don't put users or the business at risk
    • For production tests (e.g., A/B tests), explain risk mitigation strategies
    • Aim for maximum validated learning with minimal effort

  4. For each experiment, specify:

    • Assumption: What do we believe?
    • Experiment: What exactly will we do to validate it?
    • Metric: What will be measured?
    • Success threshold: The expected value if we are right

Think step by step. Present experiments in a clear table or structured format. Save as markdown if substantial.

Further Reading

© phuryn, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in pm-product-discovery/skills/brainstorm-experiments-existing of phuryn/pm-skills.

Open the folder on GitHubat commit 8607e3b

Compare with similar skills

Brainstorm Experiments Existing next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Brainstorm Experiments Existing compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Brainstorm Experiments Existing this skillphuryn/pm-skills27k—~601Automated safety check: PassMIT
Evo MemoryEvoScientist/EvoSkills4763 repos~4.8kAutomated safety check: PassApache-2.0
Suede Marketing LoopsJasonColapietro/suede-creator-skills127—~2.6kAutomated safety check: PassMIT
Idea Refinementaddyosmani/agent-skills103k6 repos~2kAutomated safety check: PassMIT
CE BrainstormEveryInc/compound-engineering-plugin25k—~1.9kAutomated safety check: PassMIT
Brainstormjlifeng/JobPilot140—~3.1kAutomated safety check: PassApache-2.0

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Categories

Questions about Brainstorm Experiments Existing

What does Brainstorm Experiments Existing do?

Design experiments to test assumptions for an existing product — prototypes, A/B tests, spikes, and other low-effort validation methods. Brainstorm Experiments Existing is an agent skill from phuryn/pm-skills. Design experiments to test assumptions for an existing product — prototypes, A/B tests, spikes, and other low-effort validation methods.

When should I use Brainstorm Experiments Existing?

Brainstorm Experiments Existing fits situations like: validating assumptions; testing feature ideas cheaply; planning product experiments.

How do I install Brainstorm Experiments Existing in Claude Code?

Run `npx skills add phuryn/pm-skills --skill brainstorm-experiments-existing -a claude-code`. Or copy the skill folder (pm-product-discovery/skills/brainstorm-experiments-existing in phuryn/pm-skills) into .claude/skills/brainstorm-experiments-existing in your project. Claude Code loads it when a task matches its description.

How do I install Brainstorm Experiments Existing in Codex?

Run `npx skills add phuryn/pm-skills --skill brainstorm-experiments-existing -a codex`. Or copy the skill folder (pm-product-discovery/skills/brainstorm-experiments-existing in phuryn/pm-skills) into .agents/skills/brainstorm-experiments-existing in your project. Codex loads it when a task matches its description.

Can I use Brainstorm Experiments Existing in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add phuryn/pm-skills --skill brainstorm-experiments-existing -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/brainstorm-experiments-existing, .gemini/skills/brainstorm-experiments-existing, .github/skills/brainstorm-experiments-existing and .opencode/skills/brainstorm-experiments-existing in your project.

What does Brainstorm Experiments Existing need to run?

SKILL.md names no scripts, command-line tools or credentials: Brainstorm Experiments Existing is instructions for the agent only.

Does Brainstorm Experiments Existing access the network?

SKILL.md names 1 domain. As links in the text: productcompass.pm. This is read from the text; nothing was executed.

Is Brainstorm Experiments Existing safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Brainstorm Experiments Existing use?

Brainstorm Experiments Existing is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Brainstorm Experiments Existing use?

About 601 tokens (SKILL.md is roughly 2.4k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Brainstorm Experiments Existing?

Skills that share tags, products or a category with Brainstorm Experiments Existing: Evo Memory (EvoScientist/EvoSkills, 476 stars), Suede Marketing Loops (JasonColapietro/suede-creator-skills, 127 stars), Idea Refinement (addyosmani/agent-skills, 103k stars) and CE Brainstorm (EveryInc/compound-engineering-plugin, 25k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Brainstorm Experiments Existing?

phuryn (a GitHub user) maintains it in phuryn/pm-skills, which has 26,845 GitHub stars. The repository holds 67 skills in this directory. The repository was last updated on September 14, 2026.

Source: phuryn/pm-skills on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.