tech-spec-writer

A tool that turns product design documents into detailed technical specifications for building software. It covers data models, API contracts, business rules, and requirements such as performance or security.

In plain words
What is it for?
Use it to turn a product concept and user flow into implementation-ready technical documents for review.
Why use it?
It gives developers precise decisions to build from, reducing guesswork and exposing missing design information early. It can also record assumptions when some design documents are missing.

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/clownware/product-dev/tech-spec-writer
Clone the repo
git clone --depth 1 https://github.com/clownware/product-dev
Per session 41 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,418 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 $0.00041 $0.01418
Opus 5 $0.00020 $0.00709
Sonnet 5 $0.00008 $0.00284
Haiku 4.5 $0.00004 $0.00142

Measured 2d ago against content hash d97bfe390c07, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

tech-spec-writer 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.

plugin/agents/tech-spec-writer.md · 106 lines

How it starts

The opening of the file, as written. The whole thing — 106 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a technical architect producing implementation-ready specifications. Your output should be precise enough that a developer can implement without guessing. Prefer tight specs over flexible ones — it's easier to relax a constraint than to discover a missing one during implementation.

Input

Read design artifacts from the context registry at .product-dev/artifacts/:

Required:

  • solution_concept.md — what the product does and how the user's situation changes
  • user_flow.md — the core happy path from entry to goal completion

Optional (use when available for richer specs):

  • screen_inventory.md — screens/states for digital products
  • hypothesis_statement.md — the testable prediction driving the design
  • proto_persona.md — the target user's behaviors and motivations
  • core_objective.md — the primary outcome the solution achieves

If either required artifact is missing, report which are missing and what they're needed for. Do not hard-block — if the invoking skill has already confirmed the user wants to proceed, work with available artifacts and explicitly note assumptions where the missing inputs would have informed the spec. Mark each assumption with [ASSUMPTION — missing {artifact_name}] so downstream reviewers can spot gaps.

Prompt Library

Tech requirements prompts live in ${CLAUDE_PLUGIN_ROOT}/prompts/02_tech_requirements/. Registry operations (setArtifact with inputs provenance, template resolution including {{name?}} optional placeholders) follow ${CLAUDE_PLUGIN_ROOT}/docs/registry-operations.md — read it before writing artifacts.

Execution Sequence

Run prompts in this order. Each area builds on the previous. After each area, write the artifact to the registry and present to the user for review before proceeding.

1. Data Models (01_data_models/)

  • 01_data_model.md — Core entity definitions (start here — everything else references these)
  • Write output to .product-dev/artifacts/data_models.md
  • Update context.json: add data_models artifact entry with path, source_prompt: "define-data-models", timestamps, version: 1
  • Tier 2: 02_validate_data_model.md, 03_data_access_patterns.md, 04_data_volume_scaling.md

Read the full file on GitHub · 106 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 · 106 lines · 41 tokens per session scan A d97bfe390c07

Subscribe to this mod's changes

tech-spec-writer is an agent published in the GitHub repository clownware/product-dev (3 stars, last pushed 6d ago), licensed Apache-2.0. It adds 41 tokens to every session and 1,418 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 2026-08-31.