spec

spec is a skill for Claude Code, Codex from helderberto/agent-skills. It costs 75 tokens per session (880 once invoked), scanned A, original, MIT.

A guide for creating a product requirements document, or PRD, by asking questions, exploring the codebase, and designing the affected modules.

In plain words
What is it for?
Use it when defining a new feature, investigating the current implementation, identifying what must be built, and saving a structured specification.
Why use it?
It helps turn an unclear feature idea into documented requirements grounded in the existing project.

Skill for Claude CodeCodex

Part of the hb plugin — 40 skills, 6 agents shipped together

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 skills/helderberto/agent-skills/spec
Any agent
npx skills add helderberto/agent-skills --skill spec
Clone the repo
git clone --depth 1 https://github.com/helderberto/agent-skills

Made for: Claude Code, Codex.

Or install hb, the plugin that ships this one along with the rest of its 40 skills, 6 agents.

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 spec

README.md
[![agentmods](https://agentmods.dev/badge/skills/helderberto/agent-skills/spec.svg)](https://agentmods.dev/skills/helderberto/agent-skills/spec)
Your own site
<a href="https://agentmods.dev/skills/helderberto/agent-skills/spec"><img src="https://agentmods.dev/badge/skills/helderberto/agent-skills/spec.svg" alt="Measured on agentmods" height="20"></a>
Per session 75 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 880 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 $0.00075 $0.00880
Opus 5 $0.00037 $0.00440
Sonnet 5 $0.00015 $0.00176
Haiku 4.5 $0.00007 $0.00088

Measured 3d ago against content hash 8cc89022c90e, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

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.

skills/spec/SKILL.md · 101 lines

How it starts

The opening of the file, as written. The whole thing — 101 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Spec

Skip satisfied steps. If argument provided, skip to Step 2.

Interactive prompts: present options as a numbered list and wait for the user's choice.

Input

The argument is: $ARGUMENTS

If empty, go to Step 1; derive slug after gathering the idea. If provided, derive slug:

  1. Take only the text before the first or (if present)
  2. Strip leading command verbs: create, build, implement, add, update, fix, make, write, plan, get, show, support
  3. Lowercase the text
  4. Remove filler words: a, an, the, for, of, to, in, on, with, and, or, but, is, be
  5. Take the first 4 remaining words (or fewer if less exist)
  6. Join with hyphens → <slug>

Output: .specs/specs/<slug>.md. If file exists, present options and wait:

  1. Overwrite existing (Recommended)
  2. Pick a new name

Workflow

1. Gather problem description

Ask the user for a detailed description of the problem and any solution ideas.

2. Explore codebase

Map current state: data models, services, API routes, frontend, tests. Note exists vs. must build.

Research protocol: codebase first, then docs. Unverifiable claims → flag as uncertain, never fabricate.

3. Interview

One question at a time. Lead with your recommended answer (mark it (Recommended) and list first). Explore code instead of asking when possible. Present 2–4 options for each question — structured choices are faster than free-text.

Branch Key questions Skip when
Scope & Surface Where? New page or integrated? Roles? CLI/library, no new entry points
Data & Concepts Definitions, existing vs missing data Never skip
Behavior Interaction patterns, filtering, search No user-facing behavior
Display Numbers, tables, charts, exports No UI
Access & Privacy Who sees what? Sensitive data? Single-user, no auth
Boundaries Out of scope, deferred features Never skip
Integration Schema, services, external deps Self-contained change

Read the full file on GitHub · 101 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 First seen · 101 lines · 75 tokens per session scan A 8cc89022c90e

Subscribe to this mod's changes

spec is a skill published in the GitHub repository helderberto/agent-skills (13 stars, last pushed 2d ago), licensed MIT. It adds 75 tokens to every session and 880 once invoked, about $0.0004 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 2026-08-30.