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.
npx skills add dhofheinz/open-plugins --skill specification-writinggit clone --depth 1 https://github.com/dhofheinz/open-pluginsWrote 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.
[](https://agentmods.dev/skills/dhofheinz/open-plugins/specification-writing)<a href="https://agentmods.dev/skills/dhofheinz/open-plugins/specification-writing"><img src="https://agentmods.dev/badge/skills/dhofheinz/open-plugins/specification-writing/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.
<a href="https://agentmods.dev/skills/dhofheinz/open-plugins/specification-writing"><img src="https://agentmods.dev/badge/skills/dhofheinz/open-plugins/specification-writing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00064 | $0.01904 |
| Opus 5.5 | $0.00026 | $0.00762 |
| Sonnet 5.5 | $0.00013 | $0.00381 |
| Haiku 4.5 | $0.00006 | $0.00190 |
Grade A, and why
specification-writing 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 1mo 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.
How it starts
The opening of the file, as written. The whole thing — 200 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Specification Writing — Core Reference
This skill is preloaded by the refinery:spec-writer agent via its skills: frontmatter field. Its content becomes part of spec-writer's system context at agent startup. This skill is not user-invocable — it has no behavior on its own; it is reference material consulted by the agent during synthesis.
The same content (in a slightly different rendering for mode/stage files) lives in ${CLAUDE_SKILL_DIR}/../refine/references/requirement-syntax.md. The two files MUST stay in sync (per NFR-M-001 single-source-of-truth discipline). When updating one, update the other.
1. EARS — Easy Approach to Requirements Syntax
EARS provides six patterns for unambiguous functional requirements. Every functional requirement (FR-NNN) MUST use one of the six patterns.
1.1 Ubiquitous (always active)
The <system> shall <required behavior>.
When to use: a behavior that holds at all times.
Example: "The system shall maintain audit logs for all administrative actions."
1.2 Event-Driven (responds to a trigger)
When <trigger>, the <system> shall <required behavior>.
When to use: a behavior that responds to a discrete event.
Example: "When a user submits a login form, the system shall validate the credentials within 200ms."
1.3 State-Driven (active during a state)
While <state>, the <system> shall <required behavior>.
When to use: a behavior that holds during a specific operational state.
Example: "While the database is in maintenance mode, the system shall reject all write requests with HTTP 503."
1.4 Unwanted Behavior (defensive)
If <unwanted condition>, then the <system> shall <required behavior>.
When to use: a behavior that handles error or exceptional conditions.
Example: "If the upstream API returns a 5xx response, then the system shall retry up to three times with exponential backoff."
1.5 Optional Feature (conditional capability)
Where <feature is included>, the <system> shall <required behavior>.
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.
- 1mo ago First seen · 200 lines · 64 tokens per session scan A 76b33c086949
specification-writing is a skill published in the GitHub repository dhofheinz/open-plugins (9 stars, last pushed 6mo ago), licensed MIT. It adds 64 tokens to every session and 1,904 once invoked, about $0.0003 per session on Opus 5.5. 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 2026-08-31.
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