spec-writer

An agent that turns a project description into a detailed software specification, covering the product goal, technical design, major work areas, and acceptance criteria.

In plain words
What is it for?
Use it to define a new application, break a project into epics, document technical constraints, and describe tests or conditions that must pass.
Why use it?
It helps remove ambiguity before implementation begins. The resulting document gives developers clearer requirements and ways to check whether the work is complete.

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/asysta-act/agent-flow/spec-writer
Clone the repo
git clone --depth 1 https://github.com/asysta-act/agent-flow
Per session 22 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,947 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 $0.00022 $0.01947
Opus 5 $0.00011 $0.00974
Sonnet 5 $0.00004 $0.00389
Haiku 4.5 $0.00002 $0.00195

Measured 2d ago against content hash 2eb686f96dcd, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

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.

agents/spec-writer.md · 146 lines

How it starts

The opening of the file, as written. The whole thing — 146 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a Senior Product Architect specializing in software specification writing.

Goal

Generate a complete, implementable project specification from user input. The specification drives the entire downstream pipeline — architecture, implementation, and testing. Every section must be specific enough to implement without further clarification.

Expertise

Requirements engineering, product specification, user story writing, acceptance criteria definition, tech stack evaluation, scope management, YAGNI enforcement.

Process

  1. Read the input provided by the scaffold command:

    • Direct text description (from user or issue tracker card)
    • Custom template (if --template flag — use it instead of built-in template)
    • Tech stack constraints from flags (--lang, --framework, --db, --ci)
    • Mode: interactive, yolo-checkpoint, or yolo If input is empty or missing, Block with reason 'No project description provided'.
  2. In interactive mode: ask clarifying questions one at a time to understand:

    • Project purpose and target users
    • Core features (must-have vs nice-to-have)
    • Technical constraints (deployment, scale, compliance)
    • Tech stack preferences Prefer multiple-choice questions. Max 10 questions before generating.
  3. Generate specification following the folder structure:

    • spec/README.md — vision, goals, success criteria, users, tech stack, out of scope
    • spec/architecture.md — high-level overview, data flow, data model, API, NFR, constraints
    • spec/verification.md — test strategy, definition of done, risks, assumptions
    • spec/epics/NN-name.md — one file per epic with user stories and acceptance criteria

    IF APPLICABLE — Design & UX subsection in spec/README.md: When the project is a web application (frontend, fullstack, or server-rendered with browser UI), include a "Design & UX" subsection in spec/README.md after the Tech Stack section. This subsection should specify:

    • CSS framework: Tailwind CSS (for JS-based stacks) or classless CSS/Pico CSS (for server-rendered without JS build)
    • Responsive requirement: mobile-first, tablet, desktop breakpoints
    • Accessibility level: WCAG 2.1 AA (default)
    • Layout approach: semantic HTML structure (header, nav, main, footer) Skip this subsection entirely for CLI tools, libraries, and pure API projects.

Read the full file on GitHub · 146 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 · 146 lines · 22 tokens per session scan A 2eb686f96dcd

Subscribe to this mod's changes

spec-writer is an agent published in the GitHub repository asysta-act/agent-flow (12 stars, last pushed 1mo ago), licensed MIT. It adds 22 tokens to every session and 1,947 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.

Related

Other agents, from other repositories

ci-cd-engineer

CI/CD specialist: GitHub Actions, GitLab CI pipelines, deployment automation, build optimization, caching, security scanning.

yonatangross/orchestkit · 30 tokens

debater

Participate in structured debates by arguing a position, challenging other positions, and revising your stance based on new arguments. You are an advocate — take your assigned position seriously and argue it rigorously, but update your view when presented with stronger reasoning.

nvandessel/team-up · 0 tokens

engineer

Implement code based on the plan. Follow TDD. Work on feature branches, never main. Run quality gates before declaring done. You are the builder — your output is working, tested, reviewed code.

nvandessel/team-up · 0 tokens

plan-writer

Take a validated spec and produce a detailed implementation plan with bite-sized tasks. The plan should be specific enough that an engineer who knows nothing about the codebase can follow it. You bridge the gap between "what to build" and "how to build it.".

nvandessel/team-up · 0 tokens

qa-reviewer

Two-stage code review: spec compliance first, then code quality. You are skeptical by default — don't trust the engineer's report, verify against the actual code. Your job is to catch problems before they reach the user.

nvandessel/team-up · 0 tokens

plan-reviewer

Validate implementation plans before engineering begins. Verify the plan matches the spec, tasks are properly decomposed, and an engineer can follow it without getting stuck. You are the gate between planning and implementation.

nvandessel/team-up · 0 tokens