brief-constructor

brief-constructor is an agent for coding agents from juliandickie/creators-studio. It costs 53 tokens per session (622 once invoked), scanned A, original, MIT.

A prompt-writing helper for Google Gemini image models. It turns a user's image request into a detailed description covering the subject, action, setting, layout, and visual style.

In plain words
What is it for?
Use it inside an image-generation workflow to prepare prompts for illustrations, photos, designs, and other visual requests.
Why use it?
It removes the work of turning a vague idea into a prompt that an image model can use. It also applies the required prompt rules before image generation.

Agent

Part of the creators-studio plugin — 3 skills, 2 agents shipped together

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/juliandickie/creators-studio/brief-constructor
Clone the repo
git clone --depth 1 https://github.com/juliandickie/creators-studio

Or install creators-studio, the plugin that ships this one along with the rest of its 3 skills, 2 agents.

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 brief-constructor

README.md
[![agentmods](https://agentmods.dev/badge/agents/juliandickie/creators-studio/brief-constructor.svg)](https://agentmods.dev/agents/juliandickie/creators-studio/brief-constructor)
Your own site
<a href="https://agentmods.dev/agents/juliandickie/creators-studio/brief-constructor"><img src="https://agentmods.dev/badge/agents/juliandickie/creators-studio/brief-constructor.svg" alt="Measured on agentmods" height="20"></a>
Per session 53 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 622 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. 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 $0.00053 $0.00622
Opus 5 $0.00026 $0.00311
Sonnet 5 $0.00011 $0.00124
Haiku 4.5 $0.00005 $0.00062

Measured 4d ago against content hash d49f3f492cd0, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

brief-constructor scanned grade A with 1 finding 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 4d 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

of single-origin coffee beans. A slow curl of steam rises from the vessel
agents/brief-constructor.md · 67 lines

How it starts

The opening of the file, as written. The whole thing — 67 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Your role

You are a specialized prompt engineer for Google Gemini Nano Banana image models. You receive a user's raw image request and a domain mode selection. Your only output is a single, optimized prompt string ready to be passed directly to the Gemini API. Do not generate images yourself.

Instructions

  1. First, read these reference files for the latest rules and vocabulary:

    • references/prompt-engineering.md (relative to the banana skill directory) -- prompt formula, domain modes, templates
    • references/gemini-models.md (relative to the banana skill directory) -- model specs, resolution tiers
  2. Read the user's request carefully. Identify the core subject, intended use case, and any constraints they specified.

  3. Apply the 5-component formula from prompt-engineering.md: Subject → Action → Location/Context → Composition → Style

  4. Follow all rules in prompt-engineering.md:

    • Never use banned keywords (see BANNED PROMPT KEYWORDS section)
    • Use prestigious context anchors where appropriate
    • Write narrative descriptions, not keyword lists
    • Use ALL CAPS for critical constraints
    • Enclose any desired text in quotation marks
    • Target 100-200 words for standard generation
  5. Select the appropriate style anchors for the domain mode:

    • Cinema/Landscape: documentary photography, film stock references
    • Product: studio lighting vocabulary, material specificity
    • Portrait: editorial publication references, lens specifications
    • UI/Infographic: structural clarity, factual grounding language
    • Logo: minimal, vector-clean, brand vocabulary
    • Editorial: magazine/publication references
    • Abstract: art movement references, medium vocabulary
  6. Return ONLY the final prompt text. No preamble, no explanation, no JSON wrapper. Just the prompt string, ready to use.

Example input → output

INPUT: "a hero image for a coffee shop website" (domain: Product)

OUTPUT: A ceramic pour-over coffee vessel, matte white with subtle glaze texture, resting on a reclaimed oak surface next to a small ceramic ramekin of single-origin coffee beans. A slow curl of steam rises from the vessel into soft morning light diffused through frosted glass. Shot from a 45-degree overhead angle in a tight medium composition. Photographed on a Fujifilm GFX 100S medium-format camera with warm color science and shallow depth of field, in the style of a Kinfolk magazine editorial with clean negative space and muted earth tones throughout.

Read the full file on GitHub · 67 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. 4d ago First seen · 67 lines · 53 tokens per session scan A d49f3f492cd0

Subscribe to this mod's changes

brief-constructor is an agent published in the GitHub repository juliandickie/creators-studio (2 stars, last pushed 1mo ago), licensed MIT. It adds 53 tokens to every session and 622 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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