generate-spec

generate-spec is a skill for Claude Code from saffron-health/libretto. It costs 30 tokens per session (1,945 once invoked), scanned A, original, MIT.

A planning tool that creates a written specification for a significant feature or complex fix in the specs/ directory. It researches the existing code and relevant library documentation, then asks important clarifying questions before writing the specification.

In plain words
What is it for?
Use it to investigate a feature or fix request, identify affected code and external libraries, gather required decisions from the user, and produce a detailed implementation plan.
Why use it?
It helps expose missing requirements, unclear decisions, and technical constraints before implementation begins.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: mentions subagents; installed under .agents/ (shared by several agents).

Part of the libretto plugin — 24 skills shipped together

Good fit Use it to investigate a feature or fix request, identify affected code and external libraries, gather required decisions from the user, and produce a detailed implementation plan.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/saffron-health/libretto/generate-spec
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 saffron-health/libretto --skill generate-spec
Clone the repo
git clone --depth 1 https://github.com/saffron-health/libretto

Made for: Claude Code.

Or install libretto, the plugin that ships this one along with the rest of its 24 skills.

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 generate-spec

README.md
[![agentmods](https://agentmods.dev/badge/skills/saffron-health/libretto/generate-spec/github.svg)](https://agentmods.dev/skills/saffron-health/libretto/generate-spec)
Your own site
<a href="https://agentmods.dev/skills/saffron-health/libretto/generate-spec"><img src="https://agentmods.dev/badge/skills/saffron-health/libretto/generate-spec/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 generate-spec

Your own site · 80×15
<a href="https://agentmods.dev/skills/saffron-health/libretto/generate-spec"><img src="https://agentmods.dev/badge/skills/saffron-health/libretto/generate-spec.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 30 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,945 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00030 $0.01945
Opus 5 $0.00015 $0.00972
Sonnet 5 $0.00006 $0.00389
Haiku 4.5 $0.00003 $0.00194

Measured 10d ago against content hash ea4748eede85, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

generate-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 10d 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.

.agents/skills/generate-spec/SKILL.md · 168 lines

How it starts

The opening of the file, as written. The whole thing — 168 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Create a spec sheet for the given feature/fix request in specs/ directory.

Ultrathink. Follow the following steps:

Understand existing code

Use code search sub-agents and grep as much as possible to deeply understand all of the relevant code. Be smart about your code search: start with where you think it might be, and if that inspires different places to read, follow up with sub-agents to do so. Each sub-agent should give you back information, and potentially other files to read or searches that might be relevant.

Understand external documentation/libraries

If external libraries are involved, always look up and research their relevant documentation as well. Tend to adhere strictly to the examples and best practices provided by the external libraries.

Ask critical guiding questions

After completing the research steps above, pause and ask the user any critical guiding questions before writing the spec. The feature/fix request will not always be completely defined. There may be logical errors, ambiguous requirements, or important clarifications required. Examples:

  • "To store this data, we could either add a new table or extend the existing X table. The new table keeps concerns separate but adds a join; extending X is simpler but couples the concepts. Which do you prefer?"
  • "There are two ways to surface this to the user: a modal dialog or an inline panel. The modal is more disruptive but harder to miss; the inline panel is less intrusive but easier to overlook. Which feels right?"
  • "We need to sync this state. We could poll on an interval or use a WebSocket. Polling is simpler to implement but adds latency; WebSocket is real-time but more complex. Which trade-off do you want?"

Present the options you see, explain the trade-offs briefly, and let the user decide. If the feature request is fully defined and the path forward is obvious, skip the questions and write the spec directly. Practice good judgement.

Establish goals and non-goals

After research and any clarifying questions, establish explicit goals and non-goals for the spec. These come directly from the user. If the user did not provide them in the initial prompt, suggest a set of goals and non-goals and ask for confirmation before proceeding.

Read the full file on GitHub · 168 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. 10d ago First seen · 168 lines · 30 tokens per session scan A ea4748eede85

Subscribe to this mod's changes

generate-spec is a skill published in the GitHub repository saffron-health/libretto (889 stars, last pushed 19d ago), licensed MIT. It adds 30 tokens to every session and 1,945 once invoked, about $0.0002 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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