spec-writer

spec-writer is a skill for Claude Code, Codex from 45ck/skill-harness. It costs 22 tokens per session (729 once invoked), scanned A, original, MIT.

A writing guide for creating specgraph specification documents with the required metadata, evidence rules, and document structure. Specgraph is a system for linking requirements to implementation and verification evidence.

In plain words
What is it for?
Use it to write feature, architecture, interface, or constraint specifications in the docs directory and define the evidence needed for each one.
Why use it?
It helps specifications follow the format that specgraph can index and check, so their status and supporting evidence are clear.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to write feature, architecture, interface, or constraint specifications in the docs directory and define the evidence needed for each one.

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Install with agentmods
npx agentmods add skills/45ck/skill-harness/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 45ck/skill-harness --skill spec-writer
Clone the repo
git clone --depth 1 https://github.com/45ck/skill-harness

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-writer

README.md
[![agentmods](https://agentmods.dev/badge/skills/45ck/skill-harness/spec-writer/github.svg)](https://agentmods.dev/skills/45ck/skill-harness/spec-writer)
Your own site
<a href="https://agentmods.dev/skills/45ck/skill-harness/spec-writer"><img src="https://agentmods.dev/badge/skills/45ck/skill-harness/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 spec-writer

Your own site · 80×15
<a href="https://agentmods.dev/skills/45ck/skill-harness/spec-writer"><img src="https://agentmods.dev/badge/skills/45ck/skill-harness/spec-writer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 22 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 729 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 $0.00022 $0.00729
Opus 5 $0.00011 $0.00365
Sonnet 5 $0.00004 $0.00146
Haiku 4.5 $0.00002 $0.00073

Measured 6d ago against content hash 08c60cda64b2, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

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 6d 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.

packs/specgraph-skills/skills/spec-writer/SKILL.md · 82 lines

How it starts

The opening of the file, as written. The whole thing — 82 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Write a spec document for the feature or component described. Place it in docs/ with a .md extension.

Spec sources: docs/ is the primary directory. specs/ is a legacy fallback.

Required frontmatter fields

---
id: <UPPERCASE-KEBAB-000>          # unique ID, e.g. AUTH-001
title: "Human-readable title"
state: draft | proposed | in_progress | accepted | done | deprecated
kind: functional | non_functional | architecture | interface | constraint
required_evidence:
  implementation: E0               # minimum evidence strength needed
  # add more dimensions as needed: verification, models, apis
# optional:
depends_on: [OTHER-001]            # IDs this spec depends on
conflicts_with: [OTHER-002]        # IDs this spec conflicts with
owner: "Team or person"
tags: [auth, security]
---

Evidence strength reference

Level Name Source
E0 Declarative @spec/@implements JSDoc annotation
E1 Structural Beads closed issue; file/symbol reference
E2 Indexed Stored in specgraph DB; linked artifact
E3 Automated Passing test suite with @spec annotation
E4 Runtime CI artifact, coverage report, live probe

State guidance

State Policy Notes
draft Always passes No evidence required — early exploration
proposed Advisory Warns if no implementation found
in_progress E1 implementation required Verification is advisory
accepted E2 impl + E2 verification + E1 models Full evidence required
done E3 impl + E3 verification + E2 models High-confidence evidence
deprecated Always passes No longer enforced

Evidence dimensions

The required_evidence block accepts any combination of:

Dimension What it tracks
implementation Code that implements the spec
verification Tests that verify the spec
models Data models referenced by the spec
apis API endpoints implementing the spec

Read the full file on GitHub · 82 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. 6d ago First seen · 82 lines · 22 tokens per session scan A 08c60cda64b2

Subscribe to this mod's changes

spec-writer is a skill published in the GitHub repository 45ck/skill-harness (15 stars, last pushed 2mo ago), licensed MIT. It adds 22 tokens to every session and 729 once invoked, about $0.0001 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 2026-09-03.