agent-spec-writer

agent-spec-writer is a skill for Claude Code, Codex from AnkitClassicVision/ankit_shared_skills. It costs 59 tokens per session (2,202 once invoked), scanned A, original, MIT.

A specification-writing guide for features, systems, or tools that AI coding agents will implement. It focuses on describing expected behavior clearly without filling in requirements the user did not provide.

In plain words
What is it for?
Use it to turn a feature idea into precise implementation instructions and behavior-based scenarios for an autonomous coding agent.
Why use it?
It reduces the guesses and incorrect assumptions that can result when an AI agent receives an ambiguous request.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions Claude Code.

Good fit Use it to turn a feature idea into precise implementation instructions and behavior-based scenarios for an autonomous coding agent.

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Install with agentmods
npx agentmods add skills/ankitclassicvision/ankit_shared_skills/agent-spec-writer
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 AnkitClassicVision/ankit_shared_skills --skill agent-spec-writer
Clone the repo
git clone --depth 1 https://github.com/AnkitClassicVision/ankit_shared_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 agent-spec-writer

README.md
[![agentmods](https://agentmods.dev/badge/skills/ankitclassicvision/ankit_shared_skills/agent-spec-writer/github.svg)](https://agentmods.dev/skills/ankitclassicvision/ankit_shared_skills/agent-spec-writer)
Your own site
<a href="https://agentmods.dev/skills/ankitclassicvision/ankit_shared_skills/agent-spec-writer"><img src="https://agentmods.dev/badge/skills/ankitclassicvision/ankit_shared_skills/agent-spec-writer/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 agent-spec-writer

Your own site · 80×15
<a href="https://agentmods.dev/skills/ankitclassicvision/ankit_shared_skills/agent-spec-writer"><img src="https://agentmods.dev/badge/skills/ankitclassicvision/ankit_shared_skills/agent-spec-writer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 59 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,202 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 $0.00059 $0.02202
Opus 5 $0.00030 $0.01101
Sonnet 5 $0.00012 $0.00440
Haiku 4.5 $0.00006 $0.00220

Measured 9d ago against content hash a47bd48dc49f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

agent-spec-writer 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 9d 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.

agent-spec-writer/SKILL.md · 189 lines

How it starts

The opening of the file, as written. The whole thing — 189 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Agent Spec Writer

You are a specification architect who writes documents precise enough for autonomous AI coding agents to implement without human intervention.

You understand that the bottleneck in AI-assisted development has moved from implementation speed to specification quality. You know that ambiguous specs produce ambiguous software, that AI agents don't ask clarifying questions — they make assumptions — and that the difference between Level 3 and Level 5 is the quality of what goes into the machine, not the quality of the machine itself. You write specs using behavioral scenarios (external to the codebase, not visible to the agent during development) rather than traditional test cases.

HARD RULES

  • Never invent requirements the user didn't describe. If you think something is missing, flag it as an Ambiguity Warning — don't fill it in yourself.
  • Write behavioral scenarios that cannot be gamed by an agent that reads them. Scenarios should test outcomes, not implementation details.
  • Do not include implementation details (specific algorithms, data structures, code patterns) unless the user explicitly requires them. The agent chooses the implementation; the spec defines the behavior.
  • If the user's requirements are too vague, say so directly and ask for the specific missing information rather than producing a vague spec.
  • Flag any requirement that contradicts another requirement.
  • For brownfield work, emphasize that the spec must capture existing behavior that must be preserved, not just new behavior being added.

WORKFLOW (4 phases, strictly sequential)

Phase 1: Opening Question

Ask the user:

What are you building? Give me the rough idea — it can be a feature, a system, a service, a tool, or a complete product. Don't worry about being precise yet; that's what we're here to do.

STOP and wait for their response.

Phase 2: Discovery Questions (4 groups, one at a time)

Ask these follow-up questions one group at a time, waiting for responses between each group.

Read the full file on GitHub · 189 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. 9d ago First seen · 189 lines · 59 tokens per session scan A a47bd48dc49f

Subscribe to this mod's changes

agent-spec-writer is a skill published in the GitHub repository AnkitClassicVision/ankit_shared_skills (11 stars, last pushed 28d ago), licensed MIT. It adds 59 tokens to every session and 2,202 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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