tech-spec

A skill that turns product design documents into technical specifications developers can implement. It produces data models, API contracts, business rules, and requirements such as security or performance, using a specialist subagent.

In plain words
What is it for?
Use it when a product concept and user flow are ready and you need detailed technical documents for implementation.
Why use it?
It checks that the key design documents exist before specification work starts and identifies missing inputs or assumptions instead of leaving requirements unclear.

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/clownware/product-dev/tech-spec
Any agent
npx skills add clownware/product-dev --skill tech-spec
Clone the repo
git clone --depth 1 https://github.com/clownware/product-dev

Made for: Claude Code, Codex.

Per session 36 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,445 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 $0.00036 $0.01445
Opus 5 $0.00018 $0.00723
Sonnet 5 $0.00007 $0.00289
Haiku 4.5 $0.00004 $0.00145

Measured 2d ago against content hash b5953bf4ed59, 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 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/skills/tech-spec/SKILL.md · 96 lines

How it starts

The opening of the file, as written. The whole thing — 96 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a technical architect helping translate product requirements into implementation-ready specifications. Your role is to produce precise, unambiguous specs that a developer can build from without guessing. Prefer specificity over flexibility — it's easier to loosen a tight spec than tighten a loose one.

Gate Check

Before starting, read .product-dev/context.json and verify:

  • solution_concept (required)
  • user_flow (required)

If either is missing:

"Technical specs need design artifacts that don't exist yet. Missing: [list]. Run /product-dev:idea to build a solution concept, then the product-flow skill to map the user flow."

Do not hard-block — if the user insists, proceed with available artifacts and explicitly note assumptions where inputs are missing.

Also read if available: screen_inventory, prototype_scope, hypothesis_statement.

Execution

Always spawn the Tech Spec Writer subagent (plugin/agents/tech-spec-writer.md). This skill delegates to the subagent because spec writing benefits from focused context and structured output.

The subagent runs the tech requirements prompt sequence from ${CLAUDE_PLUGIN_ROOT}/prompts/02_tech_requirements/:

Tier 1 Sequence

Step Prompt Path Produces Requires
1 01_data_models/01_data_model.md data_models solution_concept, user_flow
2 02_api_contracts_interfaces/01_define_api_endpoints.md api_contracts data_models, user_flow
3 03_business_logic_rules/01_define_business_rules.md business_rules data_models, user_flow
4 04_non_functional_requirements/01_performance_requirements.md nfr data_models, api_contracts, user_flow

Context-Gated Handling

  • Step 2 (define-api-endpoints): Gate: "Client-server architecture."
    • If skipping: "API endpoint specs define the contract between frontend and backend — routes, request/response schemas, error codes, auth requirements. Since this is a local-only app (or CLI tool, hardware product, etc.), there's no client-server boundary to spec. If you later add a web API or mobile backend, revisit this step — it produces endpoints.yaml for the spec package."
    • When skipping, step 4 (nfr) drops api_contracts from its requires and skips endpoint-specific performance targets.

Read the full file on GitHub · 96 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 · 96 lines · 36 tokens per session scan A b5953bf4ed59

Subscribe to this mod's changes

tech-spec is a skill published in the GitHub repository clownware/product-dev (3 stars, last pushed 6d ago), licensed Apache-2.0. It adds 36 tokens to every session and 1,445 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.