write-spec

write-spec is a skill for Claude Code from anthropics/knowledge-work-plugins. It costs 60 tokens per session (2,732 once invoked), scanned A, original, Apache-2.0.

A workflow for turning a problem or feature idea into a structured feature specification or product requirements document (PRD). It gathers users, goals, constraints, success measures, acceptance rules, and planned phases.

In plain words
What is it for?
Use it to define a new feature, clarify a user request, set acceptance criteria, or split a large initiative into phases.
Why use it?
It replaces vague requests with a shared description of what will and will not be built. This makes scope, dependencies, and ways to judge success clearer before implementation starts.

Skill for Claude Code ✓ vendor

Written for Claude Code: argument-hint in frontmatter.

Needs its repository: it reads a path above its own folder, which exists only inside the repository. The line is If you see unfamiliar placeholders or need to check which tools are connected, see [CONNECTORS.md](../../CONNECTORS.md)..

Part of the product-management plugin — 7 skills, 1 command shipped together

Good fit Use it to define a new feature, clarify a user request, set…

Compare 6 skills from other repositories ↓
About the project

Knowledge Work Plugins is an open-source collection of Claude extensions organized around roles such as productivity, sales, and customer support. Each plugin combines role-specific guidance, connectors, commands, and sub-agents so knowledge workers can use Claude with their team’s tools and processes. The catalogue entries are examples of, or workflows from, this plugin collection.

anthropics/knowledge-work-plugins · 23,902 stars · on GitHub

Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/anthropics/knowledge-work-plugins
agentmods
npx agentmods add skills/anthropics/knowledge-work-plugins/write-spec

Made for: Claude Code.

Or install product-management, the plugin that ships this one along with the rest of its 7 skills, 1 command.

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 write-spec

README.md
[![agentmods](https://agentmods.dev/badge/skills/anthropics/knowledge-work-plugins/write-spec.svg)](https://agentmods.dev/skills/anthropics/knowledge-work-plugins/write-spec)
Your own site
<a href="https://agentmods.dev/skills/anthropics/knowledge-work-plugins/write-spec"><img src="https://agentmods.dev/badge/skills/anthropics/knowledge-work-plugins/write-spec.svg" alt="Measured on agentmods" height="20"></a>
Per session 60 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,732 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 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 $0.00060 $0.02732
Opus 5 $0.00030 $0.01366
Sonnet 5 $0.00012 $0.00546
Haiku 4.5 $0.00006 $0.00273

Measured 2d ago against content hash ca6670913878, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

write-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 2d 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

Copies of this mod

6 near-identical copies found in the catalogue:

product-management/skills/write-spec/SKILL.md · 251 lines

How it starts

The opening of the file, as written. The whole thing — 251 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Write Spec

If you see unfamiliar placeholders or need to check which tools are connected, see CONNECTORS.md.

Write a feature specification or product requirements document (PRD).

Usage

/write-spec $ARGUMENTS

Workflow

1. Understand the Feature

Ask the user what they want to spec. Accept any of:

  • A feature name ("SSO support")
  • A problem statement ("Enterprise customers keep asking for centralized auth")
  • A user request ("Users want to export their data as CSV")
  • A vague idea ("We should do something about onboarding drop-off")

2. Gather Context

Ask the user for the following. Be conversational — do not dump all questions at once. Ask the most important ones first and fill in gaps as you go:

  • User problem: What problem does this solve? Who experiences it?
  • Target users: Which user segment(s) does this serve?
  • Success metrics: How will we know this worked?
  • Constraints: Technical constraints, timeline, regulatory requirements, dependencies
  • Prior art: Has this been attempted before? Are there existing solutions?

3. Pull Context from Connected Tools

If ~~project tracker is connected:

  • Search for related tickets, epics, or features
  • Pull in any existing requirements or acceptance criteria
  • Identify dependencies on other work items

If ~~knowledge base is connected:

  • Search for related research documents, prior specs, or design docs
  • Pull in relevant user research findings
  • Find related meeting notes or decision records

If ~~design is connected:

  • Pull related mockups, wireframes, or design explorations
  • Search for design system components relevant to the feature

If these tools are not connected, work entirely from what the user provides. Do not ask the user to connect tools — just proceed with available information.

4. Generate the PRD

Produce a structured PRD with these sections. See PRD Structure below for detailed guidance on what each section should contain.

Read the full file on GitHub · 251 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. 2d ago First seen · 251 lines · 60 tokens per session scan A ca6670913878

Subscribe to this mod's changes

write-spec is a skill published in the GitHub repository anthropics/knowledge-work-plugins (23,902 stars, last pushed yesterday), licensed Apache-2.0. It adds 60 tokens to every session and 2,732 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 2026-09-05.

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