Use this skill when a vague feature request, ticket, PRD fragment, or rough idea needs to be turned into a structured specification, technical plan, and ordered task breakdown for AI coding agents. Generates all three output sections immediately, then flags every implicit decision as an inline [ASSUMPTION: ...] marker with an impact rating and correction guidance — no back-and-forth questions needed before drafting. Primary keywords: spec-driven development SDD, feature specification…
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Spec Writer
Turns a vague feature request into a structured spec, technical plan, and task breakdown — ready for any coding agent to implement without guessing.
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## Overview
AI coding agents don't fail because the model is weak. They fail because the instructions are ambiguous. This skill closes that gap **before** the agent starts.
Given any feature description — a sentence, a ticket, a PRD fragment, a rough idea — spec-writer produces three deliverables in a single output:
1. **A Spec** — functional, technology-agnostic. What the feature does, who uses it, what must be true, what can go wrong, and binary acceptance criteria in Given/When/Then format.
2. **A Plan** — technical and concrete. Architecture decisions, data model changes, API contracts, testing strategy, security constraints.
3. **A Task breakdown** — ordered, self-contained tasks. Each completable in a single agent session. Each with its own acceptance criteria.
…
The line at the top of this page pins the label v1.0.0, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
GET https://markdownregistry.com/api/v1/artifacts/art_i5apzs2bgrkgeaui
GET https://markdownregistry.com/api/v1/resolve?ref=jpeetz/agent-skills/spec-writer
GET https://markdownregistry.com/api/v1/blob/0fd6e14d636b0365931638b2edb8cee4fc48347dc04d05e455e3fc88cc0c5a2f
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
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