tech-design

tech-design is a skill for Claude Code, Codex from open-octo/octo-agent. It costs 109 tokens per session (3,221 once invoked), scanned A, original, MIT.

A guided process for writing a backend technical design from a product requirements document or feature description. A technical design explains how a feature should work in code and services.

In plain words
What is it for?
Use it to explore an existing project, resolve open technical decisions, write a backend design, and review the document for unsupported names or invented scope.
Why use it?
It makes important design decisions explicit and checks them against the real codebase, documentation, and requested scope.

Skill for Claude CodeCodex

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

Good fit Use it to explore an existing project, resolve open technical decisions, write a backend design, and review the document for unsupported names or invented scope.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/open-octo/octo-agent/tech-design
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 open-octo/octo-agent --skill tech-design
Clone the repo
git clone --depth 1 https://github.com/open-octo/octo-agent

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 tech-design

README.md
[![agentmods](https://agentmods.dev/badge/skills/open-octo/octo-agent/tech-design/github.svg)](https://agentmods.dev/skills/open-octo/octo-agent/tech-design)
Your own site
<a href="https://agentmods.dev/skills/open-octo/octo-agent/tech-design"><img src="https://agentmods.dev/badge/skills/open-octo/octo-agent/tech-design/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 tech-design

Your own site · 80×15
<a href="https://agentmods.dev/skills/open-octo/octo-agent/tech-design"><img src="https://agentmods.dev/badge/skills/open-octo/octo-agent/tech-design.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 109 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,221 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 $0.00109 $0.03221
Opus 5 $0.00055 $0.01611
Sonnet 5 $0.00022 $0.00644
Haiku 4.5 $0.00011 $0.00322

Measured 9d ago against content hash a2ee1c44ec82, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

tech-design 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 9d 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.

internal/skills/defaults/tech-design/SKILL.md · 235 lines

How it starts

The opening of the file, as written. The whole thing — 235 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Skill: tech-design

Take a PRD (or feature description) and produce a complete backend technical design document through a structured process: understand → explore → grill → write → self-review.

Rules (the reason this skill exists)

These six rules run through the whole process. Follow them while writing (Phase 4), then grep for violations in the self-review. Most rework on a design doc traces back to breaking one of them.

R1. Never invent placeholders (API / field / service / URL / enum)

Every concrete technical name must be grepped from real code, looked up in docs, or asked of the user — never a plausible-sounding placeholder left for review to fix. Inventing svc.GetBookingNotes when no such method exists, or guessing a column is matter_type when it's really ticket_type, is the single most common source of production bugs that pass mocked tests.

R2. Never invent phasing

The design scope is strictly equal to the PRD scope. There are only two legal sources of phasing: (a) the PRD itself marks priority (P1/P2 in the stories), or (b) the user explicitly said "do X first, not Y" during grilling. Otherwise, if the PRD lists N sub-scenarios, design N.

Do not use P1/P2/P3 (or Phase 1/2/3) prefixes to label features, sections, or upstream links — even as "neutral numbering". A P-prefix is always read as priority/phasing and manufactures an ordering the PRD never stated. Use the PRD's own section names instead. Real execution order belongs only in a "release order" section, and only when driven by a dependency chain, not by scope-cutting.

R3. Technical facts must be traceable

Every concrete technical claim (DB column, URL prefix, field, API signature, enum value, cache key pattern, MQ topic) must come from one of: a code location (file:line), project docs, or a grill answer (quote the decision). Can't find a source → ask the user (they're online; asking is cheap). Never paper over a gap with a TODO.

Decision-level choices (sync vs async, new table vs extend column) can rest on a grill answer plus explicit trade-off reasoning — but factual assertions must be greppable.

Read the full file on GitHub · 235 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. 9d ago First seen · 235 lines · 109 tokens per session scan A a2ee1c44ec82

Subscribe to this mod's changes

tech-design is a skill published in the GitHub repository open-octo/octo-agent (97 stars, last pushed yesterday), licensed MIT. It adds 109 tokens to every session and 3,221 once invoked, about $0.0005 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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