C31-brainstorm

C31-brainstorm is a skill for Claude Code, Codex from ChianW/C31. It costs 38 tokens per session (4,018 once invoked), scanned A, original, MIT.

A structured brainstorming guide for deciding what to build before planning how to build it. It turns a discussion into a requirements document with numbered decisions that can be followed during planning.

In plain words
What is it for?
Use it to discuss ideas, clarify feature requirements one question at a time, record decisions and assumptions, and prepare a requirements document for the planning stage.
Why use it?
It reduces vague requirements, hidden assumptions, and decisions being changed without notice later. It gives the project a written record of what was agreed.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions CLAUDE.md; mentions subagents; mentions AGENTS.md.

Good fit Use it to discuss ideas, clarify feature requirements one question at a time, record decisions and assumptions, and prepare a requirements document for the planning stage.

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Install with agentmods
npx agentmods add skills/chianw/c31/c31-brainstorm
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 ChianW/C31 --skill c31-brainstorm
Clone the repo
git clone --depth 1 https://github.com/ChianW/C31

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 C31-brainstorm

README.md
[![agentmods](https://agentmods.dev/badge/skills/chianw/c31/c31-brainstorm.svg)](https://agentmods.dev/skills/chianw/c31/c31-brainstorm)
Your own site
<a href="https://agentmods.dev/skills/chianw/c31/c31-brainstorm"><img src="https://agentmods.dev/badge/skills/chianw/c31/c31-brainstorm.svg" alt="Measured on agentmods" height="20"></a>
Per session 38 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,018 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 $0.00038 $0.04018
Opus 5 $0.00019 $0.02009
Sonnet 5 $0.00008 $0.00804
Haiku 4.5 $0.00004 $0.00402

Measured 8d ago against content hash 7111513dc86e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

C31-brainstorm 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/core/C31-brainstorm/SKILL.md · 336 lines

How it starts

The opening of the file, as written. The whole thing — 336 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Multilingual Triggers

Language Trigger phrases
EN brainstorm, ideate, think through, 需求, discuss, 讨论, discuss-phase
ZH 头脑风暴, 讨论需求, 讨论一下
JA ブレインストーミング, 考えてみよう, 議論しよう

Output language: Respond automatically in the user's conversation language.

C31 Brainstorm — Discuss Phase

Brainstorming answers WHAT to build. It precedes planning, which answers HOW to build it.

The durable output is a requirements document with numbered, traceable decisions (D-01, D-02...) that MUST carry forward into planning. No decision made here should be silently re-invented later.

Guardrails: Anti-Rationalization Table

When requirements are fuzzy, agents commonly rationalize skipping structured discovery. Call yourself out.

Excuse Why It's Wrong Correct Approach
"The user will tell me" Users assume you already understand; they won't proactively fill in gaps Actively extract, one question at a time
"Assume first, adjust later" Assumptions will contaminate all downstream reasoning Mark as A-XX, wait for confirmation
"Open-ended questions are efficient" Users faced with a blank will skip or give vague answers Offer options to narrow the answer space
"It's already clear enough" Your "clear" ≠ the user's "clear" Validate with concrete scenarios
"Asking more will annoy the user" Rework after delivery is far more annoying Every question has ROI

Rule of thumb: If you can't write down 3 specific acceptance criteria right now, you don't understand the requirement well enough to plan.

Interview-me Mode

A structured variant of Phase 1.3 for when the user's request is genuinely ambiguous — not merely underspecified, but the problem space itself is unclear.

When to Activate

  • You can't articulate the user's goal in one sentence
  • You can't list 3 concrete acceptance criteria
  • Your internal confidence score is < 70%
  • The user said "I want to build a..." / "Can you help me..." with no follow-up detail

Read the full file on GitHub · 336 lines

Files

What ships with it

1 file 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.

  1. 8d ago First seen · 336 lines · 38 tokens per session scan A 7111513dc86e

Subscribe to this mod's changes

C31-brainstorm is a skill published in the GitHub repository ChianW/C31 (1 stars, last pushed 13d ago), licensed MIT. It adds 38 tokens to every session and 4,018 once invoked, about $0.0002 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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