spec

spec is a skill for Claude Code, Codex from brsbl/ottonomous. It costs 88 tokens per session (1,291 once invoked), scanned A, original, MIT.

A product-specification writing workflow that researches the codebase and, when needed, the web before drafting or revising a product specification. A product specification is a document describing what a product or feature should do.

In plain words
What is it for?
Use it to plan a feature, define requirements, revise a specification, or create a product requirements document.
Why use it?
It turns an idea or existing draft into a researched, reviewed specification while preserving the requested destination and user-provided content.

Skill for Claude CodeCodex

Part of the ottonomous plugin — 3 skills, 4 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/brsbl/ottonomous/spec
Any agent
npx skills add brsbl/ottonomous --skill spec
Clone the repo
git clone --depth 1 https://github.com/brsbl/ottonomous

Made for: Claude Code, Codex.

Or install ottonomous, the plugin that ships this one along with the rest of its 3 skills, 4 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/brsbl/ottonomous/spec.svg)](https://agentmods.dev/skills/brsbl/ottonomous/spec)
Your own site
<a href="https://agentmods.dev/skills/brsbl/ottonomous/spec"><img src="https://agentmods.dev/badge/skills/brsbl/ottonomous/spec.svg" alt="Measured on agentmods" height="20"></a>
Per session 88 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,291 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 $0.00088 $0.01291
Opus 5 $0.00044 $0.00646
Sonnet 5 $0.00018 $0.00258
Haiku 4.5 $0.00009 $0.00129

Measured 4d ago against content hash 1f65c3c6c5e2, 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 4d 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.

plugins/ottonomous/skills/spec/SKILL.md · 170 lines

How it starts

The opening of the file, as written. The whole thing — 170 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Input: $ARGUMENTS

Create or revise one product specification. The caller may provide the idea or draft inline, as a file reference, or through the surrounding conversation.

Resolve the invocation

Identify these inputs from the caller's request:

  • Source: product idea, inline draft, or existing spec reference
  • Working location: codebase or context to research
  • Output destination: caller-selected file or external destination
  • Format constraints: optional template, frontmatter, note system, or style

Ask only for information that blocks useful progress. An existing spec file can serve as its own destination. Otherwise, if the caller omits an output destination, ask for one before drafting. Never invent a spec registry, fixed directory, hidden state file, duplicate copy, or symlink. Use exactly the caller-selected destination and keep any supporting assets beside it or in a caller-selected asset location.

When revising an existing file, read it completely before editing. Preserve user-authored content, required metadata, comments, links, and layout unless a requested change requires otherwise.

1. Gather product and codebase context

For a new idea, ask whether reference products or examples matter. For an existing draft, treat its decided requirements as constraints rather than reopening them without evidence.

Inspect the supplied working location:

  • Find the relevant files, interfaces, data models, and product surfaces.
  • Trace the current behavior and name important architectural constraints.
  • Search repository history when the proposal changes a public contract or a previously decided behavior.
  • Separate observed facts from assumptions and open decisions.

If no working location is supplied, continue with product discovery and mark codebase-dependent claims as assumptions.

2. Research the problem

Use web research when current external evidence would improve the decision:

  • Primary documentation for APIs, platforms, standards, or constraints
  • Established product patterns and comparable implementations
  • Known failure modes, security concerns, and accessibility expectations

Read the full file on GitHub · 170 lines

Files

What ships with it

2 files 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. 4d ago First seen · 170 lines · 88 tokens per session scan A 1f65c3c6c5e2

Subscribe to this mod's changes

spec is a skill published in the GitHub repository brsbl/ottonomous (15 stars, last pushed 10d ago), licensed MIT. It adds 88 tokens to every session and 1,291 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.

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