Technical Design Document skill for Claude and Codex

Technical Design Document as an AI skill. It asks for Project name, Problem, Scale and constraints and 4 more, then does the rest. Free to install in Claude…

Install it once and Claude or Codex runs it for you. When your request matches, your AI loads the skill, asks for anything it is missing, and works through the template itself. Prefer to fill it in by hand? See the full prompt template.

Download the skill (.zip) · View SKILL.md

When it is used

Use when an engineer is about to start a substantial project and needs a design doc with goals, non-goals, alternatives, risks and rollout for review. Do not use for recording a single decision or writing user-facing documentation. Related topics: coding, writing.

What it will ask you for

• Project name (free text, e.g. "Short name")
• Problem (longer free text)
• Scale and constraints (longer free text)
• Rough approach (longer free text)
• Systems it touches (longer free text)
• Reviewers (free text, e.g. "Who needs to sign off")
• Document length (choose one: One page, Three pages, Full detail)

How it works

1. State the problem with measurable goals and write non-goals that fence the scope.
2. Describe the design through components, data flow, interfaces, data changes and failure behaviour at reviewer level.
3. Add at least two alternatives, each with the specific reason it was not chosen.
4. Cover security, testing, observability and a rollout order with a way to back out.
5. List risks and open questions with owners, and flag every assumption the author must confirm.

What you get

A design document sized to the chosen length with these sections in order: problem, goals, non-goals, design, alternatives, risks, rollout, open questions and milestones.

What it watches out for

• Skipping non-goals, so reviewers debate features the project never meant to cover.
• Presenting one design with no alternatives, which turns review into approval theatre.
• Describing the happy path only, when most review comments concern failure and migration.

How to install

Claude.ai and the Claude desktop app

1. Download the skill .zip.
2. Open Settings, then Capabilities, and find Skills.
3. Choose Upload skill and select the .zip.
4. Ask Claude for help with the task. It loads the skill when your request matches.

Claude Code

1. Download the skill .zip.
2. Unzip it into ~/.claude/skills/ (or .claude/skills/ inside a project).
3. Start a new session. Claude Code loads the skill when your request matches.

Codex

1. Download the skill .zip.
2. Unzip it into ~/.agents/skills/ (or .agents/skills/ inside a project).
3. Codex picks it up on its own. Type $ and the skill name to use it, or just ask for the task.

Cursor

1. Download the Cursor rule (.mdc).
2. Save it in .cursor/rules/ inside your project.
3. Cursor's agent applies the rule when your request matches its description.

AGENTS.md (Codex, Cursor, and other coding agents)

1. Copy the AGENTS.md section.
2. Paste it into AGENTS.md at the root of your repository, creating the file if needed.
3. Coding agents that read AGENTS.md follow it when your request fits.