gen-spec

gen-spec is a skill for Claude Code from pe-menezes/vibeflow-claude. It costs 74 tokens per session (1,570 once invoked), scanned A, a copy of gen-spec, MIT.

A tool for turning clear requirements into a technical specification: what will be built, what counts as complete, what is included, what is excluded, and which technical choices apply. A Definition of Done is a list of checks that can each be answered yes or no.

In plain words
What is it for?
Use it to prepare an implementation-ready spec, define completion checks, record decisions, and split an oversized spec into smaller ones.
Why use it?
It makes the expected result and boundaries explicit before implementation starts, while grounding the plan in patterns already used by the project.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

Part of the vibeflow plugin — 10 skills, 1 agent shipped together

Good fit Use it to prepare an implementation-ready spec, define completion checks, record decisions, and split an oversized spec into smaller ones.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/pe-menezes/vibeflow-claude/gen-spec
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 pe-menezes/vibeflow-claude --skill gen-spec
Clone the repo
git clone --depth 1 https://github.com/pe-menezes/vibeflow-claude

Made for: Claude Code.

Or install vibeflow, the plugin that ships this one along with the rest of its 10 skills, 1 agent.

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 gen-spec

README.md
[![agentmods](https://agentmods.dev/badge/skills/pe-menezes/vibeflow-claude/gen-spec/github.svg)](https://agentmods.dev/skills/pe-menezes/vibeflow-claude/gen-spec)
Your own site
<a href="https://agentmods.dev/skills/pe-menezes/vibeflow-claude/gen-spec"><img src="https://agentmods.dev/badge/skills/pe-menezes/vibeflow-claude/gen-spec/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 gen-spec

Your own site · 80×15
<a href="https://agentmods.dev/skills/pe-menezes/vibeflow-claude/gen-spec"><img src="https://agentmods.dev/badge/skills/pe-menezes/vibeflow-claude/gen-spec.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 74 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,570 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 88% copy Near-identical to another mod 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 $0.00074 $0.01570
Opus 5 $0.00037 $0.00785
Sonnet 5 $0.00015 $0.00314
Haiku 4.5 $0.00007 $0.00157

Measured 3d ago against content hash 9ba6a8a9ba97, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

gen-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 3d 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.

Origin

This is a copy

88% identical to gen-spec — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/gen-spec/SKILL.md · 132 lines

How it starts

The opening of the file, as written. The whole thing — 132 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Description and examples

What it does: Produces a technical spec in .vibeflow/specs/<slug>.md with objective, Definition of Done (3–7 binary checks), scope, anti-scope, technical decisions, and applicable patterns. Reads .vibeflow/ to ground the spec in your project. Can take a PRD path (from discover) or a short feature description.

Examples:

  • gen-spec .vibeflow/prds/login-flow.md — Generate spec from an existing PRD.
  • gen-spec adicionar endpoint POST /auth/login que retorna JWT — Generate spec from a one-line description (uses .vibeflow/ patterns).

Language

Detect the language of the user's current request or conversation. Write ALL output in that same language. Technical terms in English are acceptable regardless of the detected language. One heading is exempt: ## References stays literally in English in any output language — prompt-pack's propagation matches that exact heading.

Web Search Policy

Use WebSearch and WebFetch only when local context (.vibeflow/, codebase, git history) is insufficient — an unfamiliar framework or API. Local first.

Generate a complete spec for the feature in the user's current request.

Before writing the spec

  1. Read the input. A path to a .md inside .vibeflow/prds/ is a PRD: problem, audience, solution, scope, and anti-scope are already settled — your job is translating them into technical decisions, binary DoD checks, and applicable patterns. Anything else is a feature description.
  2. Load context from .vibeflow/, if it exists:
    • index.md — project context. Its Suggested budget: ≤ N line is this spec's budget; without it, ≤6 files.
    • conventions.md — the project's standards.
    • Patterns: read the ## Pattern Registry block in index.md (between <!-- vibeflow:patterns:start/end --> markers), cross-reference its tags and modules against the feature, and load the top 3–5 matches. With no registry, fall back to reading all pattern docs.

Read the full file on GitHub · 132 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. 3d ago Changed · -1 lines 9ba6a8a9ba97
  2. 10d ago First seen · 133 lines · 74 tokens per session scan A 3cdc08bd6724

Subscribe to this mod's changes

gen-spec is a skill published in the GitHub repository pe-menezes/vibeflow-claude (2 stars, last pushed 4d ago), licensed MIT. It adds 74 tokens to every session and 1,570 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. It is 88% identical to gen-spec, differing in 0 lines, and is treated as a copy.

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