technical-spec

technical-spec is a skill for Claude Code, Codex from majiayu000/spellbook. It costs 39 tokens per session (3,087 once invoked), scanned A, original, MIT.

A guide for writing technical specifications, RFCs, architecture decision records, and other design documents. These documents explain how a system should work and why particular choices were made.

In plain words
What is it for?
Use it to document system designs, compare technology choices, create architecture diagrams, and record alternatives and trade-offs.
Why use it?
It helps teams think through decisions before coding and preserve the reasoning as the system changes.

Skill for Claude CodeCodex

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

Good fit Use it to document system designs, compare technology choices, create architecture diagrams, and record alternatives and trade-offs.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/majiayu000/spellbook/technical-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 majiayu000/spellbook --skill technical-spec
Clone the repo
git clone --depth 1 https://github.com/majiayu000/spellbook

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 technical-spec

README.md
[![agentmods](https://agentmods.dev/badge/skills/majiayu000/spellbook/technical-spec/github.svg)](https://agentmods.dev/skills/majiayu000/spellbook/technical-spec)
Your own site
<a href="https://agentmods.dev/skills/majiayu000/spellbook/technical-spec"><img src="https://agentmods.dev/badge/skills/majiayu000/spellbook/technical-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 technical-spec

Your own site · 80×15
<a href="https://agentmods.dev/skills/majiayu000/spellbook/technical-spec"><img src="https://agentmods.dev/badge/skills/majiayu000/spellbook/technical-spec.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 39 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,087 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 warn 7 Sept 2026
SkillSpector: 3 findings, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high Privilege Escalation · line 197
    Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.
    Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
  • high Privilege Escalation · line 210
    Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.
    Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
  • high Privilege Escalation · line 212
    Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.
    Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
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 $0.00039 $0.03087
Opus 5 $0.00019 $0.01543
Sonnet 5 $0.00008 $0.00617
Haiku 4.5 $0.00004 $0.00309

Measured 8d ago against content hash bba72718b970, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

technical-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 8d 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/technical-spec/SKILL.md · 474 lines

How it starts

The opening of the file, as written. The whole thing — 474 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Technical Specification & Design Documents

Expert guidance for writing effective technical design documents, RFCs, Architecture Decision Records, and technology evaluation frameworks.

Core Philosophy

  • Write before code — Design documents prevent costly rework and align teams
  • Living documents — Keep docs updated as the system evolves
  • Clarity over completeness — Simple, direct language reduces cognitive load
  • Diagrams as code — Version-controlled, maintainable architecture diagrams
  • Decisions over descriptions — Document why, not just what

Hard Rules (Must Follow)

These rules are mandatory. Violating them means the skill is not working correctly.

Alternatives Required

Every design document must include at least 2 alternative solutions.

❌ FORBIDDEN:
## Solution
We will use PostgreSQL for the database.
(No alternatives considered)

✅ REQUIRED:
## Proposed Solution
PostgreSQL for primary database.

## Alternatives Considered

### Option A: PostgreSQL (Recommended)
**Pros**: ACID compliance, JSON support, mature ecosystem
**Cons**: Vertical scaling limits
**Decision**: Chosen for reliability and team expertise

### Option B: MongoDB
**Pros**: Horizontal scaling, flexible schema
**Cons**: Eventual consistency, less familiar to team
**Decision**: Rejected due to consistency requirements

### Option C: DynamoDB
**Pros**: Serverless, auto-scaling
**Cons**: Vendor lock-in, complex query patterns
**Decision**: Rejected due to query flexibility needs

Diagrams Required

System designs must include architecture diagrams. No text-only descriptions.

❌ FORBIDDEN:
"The user sends a request to the API, which talks to the database
and returns a response."

✅ REQUIRED:
Include at least one of:
- C4 Context/Container diagram
- Sequence diagram for key flows
- Data flow diagram

Example (Mermaid):
```mermaid
sequenceDiagram
    Client->>API: POST /orders
    API->>Auth: Validate token
    Auth-->>API: User context
    API->>DB: Create order
    DB-->>API: Order ID
    API-->>Client: 201 Created

Read the full file on GitHub · 474 lines

Files

What ships with it

7 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 8d ago First seen · 474 lines · 39 tokens per session scan A bba72718b970

Subscribe to this mod's changes

technical-spec is a skill published in the GitHub repository majiayu000/spellbook (278 stars, last pushed yesterday), licensed MIT. It adds 39 tokens to every session and 3,087 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 2026-09-03.

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