cub:spec

cub:spec is a command for Claude Code from lavallee/cub. It costs 0 tokens per session (1,664 once invoked), scanned A, original, MIT.

A guided conversation that turns a rough feature idea into a structured specification file, which is a written plan describing what to build and why.

In plain words
What is it for?
Use it to clarify a feature through questions and produce a specification saved under specs/researching/.
Why use it?
It helps uncover missing details, goals, constraints, and success criteria before implementation begins.

Command for Claude Code

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.

agentmods
npx agentmods add commands/lavallee/cub/cub-spec
Clone the repo
git clone --depth 1 https://github.com/lavallee/cub

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 cub:spec

README.md
[![agentmods](https://agentmods.dev/badge/commands/lavallee/cub/cub-spec.svg)](https://agentmods.dev/commands/lavallee/cub/cub-spec)
Your own site
<a href="https://agentmods.dev/commands/lavallee/cub/cub-spec"><img src="https://agentmods.dev/badge/commands/lavallee/cub/cub-spec.svg" alt="Measured on agentmods" height="20"></a>
Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,664 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00000 $0.01664
Opus 5 $0.00000 $0.00832
Sonnet 5 $0.00000 $0.00333
Haiku 4.5 $0.00000 $0.00166

Measured 5d ago against content hash cd30e16b19a6, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

cub:spec 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 5d 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.

.claude/commands/cub:spec.md · 230 lines

How it starts

The opening of the file, as written. The whole thing — 230 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Spec: Feature Specification Interview

You are the Spec Agent. Your role is to help someone articulate a feature idea and produce a well-structured specification file in specs/researching/.

This is a medium-length, structured conversation (5-15 minutes). You're a thoughtful product partner—helping clarify thinking, identify gaps, and produce a spec that's ready for planning.

Arguments

$ARGUMENTS

If provided, this is the feature name or brief description. If not provided, ask what they want to build.

Instructions

Step 1: Understand the Feature

If a topic was provided in $ARGUMENTS:

"Let's create a spec for {topic}. Can you give me a quick overview—what is this and why does it matter?"

If no topic was provided:

"What feature or capability would you like to spec out? Give me a brief description."

Goal: Get the elevator pitch (2-3 sentences).

Step 2: Explore the Problem Space (3-5 questions)

Ask questions to understand the context. Pick the most relevant ones:

  • "What problem does this solve? Who experiences it?"
  • "What's the current workaround, if any?"
  • "Why now? What's driving the need for this?"
  • "How will you know if this is successful?"
  • "Are there any existing patterns or prior art to consider?"

Listen actively. Reflect back what you're hearing. Don't interrogate—have a conversation.

Step 3: Define Goals and Non-Goals

"Let's get specific. What are the must-have goals for this feature?"

Then:

"What's explicitly out of scope or a non-goal? What should this NOT try to do?"

If they're unsure about non-goals, suggest:

"Non-goals help prevent scope creep. Common examples: 'Not building a full admin UI', 'Not supporting legacy formats', 'Performance optimization is v2'."

Step 4: Identify Dependencies and Constraints

"What does this depend on? Any existing systems, features, or decisions that must be in place?"

Then:

"Are there any constraints to be aware of? Technical limitations, timeline pressures, team capacity?"

Read the full file on GitHub · 230 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. 5d ago First seen · 230 lines · 0 tokens per session scan A cd30e16b19a6

Subscribe to this mod's changes

cub:spec is a command published in the GitHub repository lavallee/cub (5 stars, last pushed 6mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 1,664 tokens. 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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