spec

spec is a skill for Claude Code, Codex from eigent-ai/agent-skills. It costs 52 tokens per session (383 once invoked), scanned A, original, Apache-2.0.

A skill for writing a detailed product or engineering specification before implementation. It records the problem, goals, requirements, user cases, acceptance checks, risks, and unresolved decisions.

In plain words
What is it for?
Preparing feature plans, product requirement documents, API specifications, refactor plans, user stories, and acceptance criteria.
Why use it?
It reduces ambiguity before coding and makes expected behavior and edge cases clear to everyone involved.

Skill for Claude CodeCodex

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

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 spec

README.md
[![agentmods](https://agentmods.dev/badge/skills/eigent-ai/agent-skills/spec.svg)](https://agentmods.dev/skills/eigent-ai/agent-skills/spec)
Your own site
<a href="https://agentmods.dev/skills/eigent-ai/agent-skills/spec"><img src="https://agentmods.dev/badge/skills/eigent-ai/agent-skills/spec.svg" alt="Measured on agentmods" height="20"></a>
Per session 52 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 383 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 $0.00052 $0.00383
Opus 5 $0.00026 $0.00192
Sonnet 5 $0.00010 $0.00077
Haiku 4.5 $0.00005 $0.00038

Measured 5d ago against content hash 522cbaaede0a, 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 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.

skills/coding-agents-and-ides/spec/SKILL.md · 41 lines

What it actually says

Spec

Overview

Use this skill to turn a feature, API, refactor, or product idea into a clear specification that can feed planning and implementation. The output should reduce ambiguity before code is written.

Workflow

  1. Identify the problem, goal, users, constraints, and non-goals.
  2. Capture the current behavior or system context when relevant.
  3. Define user stories or use cases with acceptance criteria.
  4. Specify functional requirements, edge cases, error states, permissions, and data handling.
  5. Include API, UI, migration, observability, performance, or rollout requirements when applicable.
  6. List open decisions and assumptions explicitly.
  7. Keep the spec implementation-aware but avoid over-prescribing internal code structure unless required.

Output Pattern

Use this structure by default:

  1. Summary.
  2. Problem statement.
  3. Goals and non-goals.
  4. Users and use cases.
  5. Requirements.
  6. Acceptance criteria.
  7. Edge cases and risks.
  8. Observability, rollout, and rollback notes.
  9. Open questions.

Example Prompts

  • /spec - Build a CSV export feature for our analytics dashboard. Users need to export filtered data with custom date ranges. Support up to 100k rows.
  • /spec - Design a public webhooks API for our platform. Third-party apps need to subscribe to user events and receive payloads reliably with retry logic.
  • /spec - Refactor our authentication flow to support SSO. We need to keep existing email/password working and add Google and GitHub OAuth without breaking current sessions.
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 · 41 lines · 52 tokens per session scan A 522cbaaede0a

Subscribe to this mod's changes

spec is a skill published in the GitHub repository eigent-ai/agent-skills (17 stars, last pushed 3mo ago), licensed Apache-2.0. It adds 52 tokens to every session and 383 once invoked, about $0.0003 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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