spec

A guided workflow for researching and writing a design specification or Architecture Decision Record (ADR), which records an important technical choice and its reasoning.

In plain words
What is it for?
Use it to compare technical approaches, investigate risks, ask decision-shaping questions, and define tests with clear success criteria.
Why use it?
It exposes assumptions, edge cases, and validation needs before implementation begins.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/wrannaman/agentic-engineering/spec
Any agent
npx skills add wrannaman/agentic-engineering --skill spec
Clone the repo
git clone --depth 1 https://github.com/wrannaman/agentic-engineering

Made for: Claude Code, Codex.

Per session 21 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,479 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00021 $0.03479
Opus 5 $0.00010 $0.01740
Sonnet 5 $0.00004 $0.00696
Haiku 4.5 $0.00002 $0.00348

Measured 2d ago against content hash 1323bc33d343, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

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 2d 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.

skills/analysis/spec/SKILL.md · 439 lines

How it starts

The opening of the file, as written. The whole thing — 439 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Design Spec Writer

You are helping the user write an excellent design spec, which will be saved as an Architecture Decision Record (ADR) in the decisions/ directory.

Your Role

You are NOT writing the spec for the user. Instead, you are ACTIVELY guiding them to make better decisions:

  1. Deep Research - Don't just find patterns, INVESTIGATE approaches to uncover thorny edges
  2. Proactive Gotcha Hunting - Before suggesting any approach, research what could go wrong
  3. Critical Questioning - Surface questions that challenge assumptions and reveal unknowns
  4. Validation Recommendations - Don't just suggest validation is possible - RECOMMEND specific tests with clear success criteria
  5. Learning Integration - Apply past learnings to avoid repeating mistakes

BE ACTIVE, NOT PASSIVE. Don't just present options neutrally - dig into them, find the edge cases, identify what MUST be validated, and recommend the validation approach.

Four Pillars of a Great Spec

Every excellent spec has these four qualities:

  1. Good Background - Written as if the reader knows nothing about the domain. An AI agent should be able to ingest it easily.
    • Explain the domain from first principles — what makes it unique?
    • Identify what's shared with familiar patterns and what's genuinely different
    • Avoid false dichotomies ("X is nothing like Y") — be precise about similarities and differences
    • Include a recovery/strategy table when the design involves error handling
    • The reader should finish the background section with enough context to evaluate the design choices
  2. Code Snippets - Especially for interface boundaries and API contracts. Show concrete examples.
  3. Implementation Suggestions - Guidance on how to implement WITHOUT getting bogged down in details.
  4. Realistic Scalability Concerns - Address real-world scaling considerations.

Optional but valuable: Alternatives considered and why they were rejected.

Incorporating Learnings

Read the full file on GitHub · 439 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. 2d ago First seen · 439 lines · 21 tokens per session scan A 1323bc33d343

Subscribe to this mod's changes

spec is a skill published in the GitHub repository wrannaman/agentic-engineering (2 stars, last pushed 4mo ago), licensed MIT. It adds 21 tokens to every session and 3,479 once invoked, about $0.0001 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 2026-08-31.

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