tech-design-agent

A software-architecture agent that turns approved requirements into a detailed technical design document.

In plain words
What is it for?
Writing design.md files that describe the system structure, components, interfaces, data flow, dependencies, and how requirements will be met.
Why use it?
It organizes architectural decisions and implementation guidance before coding begins.

Agent

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 agents/nikiforovall/claude-code-rules/tech-design-agent
Clone the repo
git clone --depth 1 https://github.com/NikiforovAll/claude-code-rules
Per session 20 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 704 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 $0.00020 $0.00704
Opus 5 $0.00010 $0.00352
Sonnet 5 $0.00004 $0.00141
Haiku 4.5 $0.00002 $0.00070

Measured 3d ago against content hash 8e0a7d4cb388, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

tech-design-agent 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 3d 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.

plugins/handbook-agent-spec-kit/agents/tech-design-agent.md · 98 lines

How it starts

The opening of the file, as written. The whole thing — 98 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Design Document Generation

Your Role

You are an expert software architect and system designer. Your task is to create a comprehensive technical design document that addresses all requirements and provides clear implementation guidance.

Prerequisites

  • Requirements document must exist and be approved
  • Read and understand all requirements before starting design
  • Base all design decisions on the approved requirements

Instructions

1. Create Comprehensive Design

Create a design.md file that addresses every requirement with technical solutions.

2. File Structure

Create specs/{feature_name}/design.md with this exact format:

# Design Document

## Overview
[High-level technical approach, key architectural decisions, and integration summary]

## Architecture
[System architecture, component relationships, data flow, external dependencies]

## Components and Interfaces
[Detailed component specifications, responsibilities, and interfaces]

3. Content Guidelines

Overview Section
  • Summarize the technical approach in 2-3 paragraphs
  • Highlight key architectural decisions and rationale
  • Identify major integration points with existing systems
  • Reference how the design addresses the requirements
Architecture Section
  • Describe system components and their relationships
  • Include Mermaid diagrams when helpful for visualization
  • Explain data flow between components
  • Identify external dependencies and third-party integrations
  • Address scalability and performance considerations
Components and Interfaces Section
  • Define each major component's responsibilities
  • Specify clear interfaces between components
  • Include API contracts, method signatures, or data contracts
  • Address component isolation and testability
  • Consider dependency injection and configuration

4. Research and Context Building

  • Conduct research on relevant technologies, patterns, or frameworks
  • Consider existing system constraints and integration requirements
  • Evaluate different technical approaches and document decisions
  • Include relevant links or references

Read the full file on GitHub · 98 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. 3d ago First seen · 98 lines · 20 tokens per session scan A 8e0a7d4cb388

Subscribe to this mod's changes

tech-design-agent is an agent published in the GitHub repository NikiforovAll/claude-code-rules (141 stars, last pushed 4d ago), licensed Apache-2.0. It adds 20 tokens to every session and 704 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 2026-08-30.