Agent skill

Image Gen

by notque in notque/vexjoy-agent

AI image generation: Gemini and Nano Banana backends; single/series/batch workflows with prompt-to-disk.

MITAuto-check passedMedia & Creative

Install Image Gen

skills CLI
$ npx skills add notque/vexjoy-agent --skill image-gen -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install notque/vexjoy-agent image-gen --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/notque/vexjoy-agent.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/content/image-gen .claude/skills/image-gen && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
image-gen
GitHub stars
435
Token cost
~1.3k tokens
SKILL.md length
458 words
Files
7 (incl. scripts, references)
Skills in repo
61
Repo updated
First seen
Licence
MIT

At a glance

AI image generation: Gemini and Nano Banana backends; single/series/batch workflows with prompt-to-disk.

  • Works in 5 steps: Detect Backend → Write Prompt Files → Select Script → …
  • Tasks that involve Image generation
  • SKILL.md covers Deep References, Phase 1: Detect Backend, Phase 2: Write Prompt Files and Phase 3: Select Script, plus 3 more sections
  • Runs Python scripts from its folder; calls python3 and pip; needs GEMINI_API_KEY

What it does

Image Gen is an agent skill from notque/vexjoy-agent. AI image generation: Gemini and Nano Banana backends; single/series/batch workflows with prompt-to-disk.

Its SKILL.md is about 1.3k tokens, which your agent loads only when the skill is triggered. The skill folder holds 9 other files, including scripts and reference files (for example `references/backends/gemini.md`, `references/backends/nano-banana.md` and `scripts/detect-backend.py`).

It sits in Media & Creative, covering Image generation. It works with Google Gemini. The repository describes itself as: VexJoy AI Agent with Jev Intelligent Routing - /do routes plain-English requests to the right specialist agent and gates the work with reviews, tests, and a learning loop. The licence is MIT.

When your agent uses it

  • Tasks that involve Image generation

Example prompts

  • “/image-gen”

Requirements

  • Python 3
  • A credential in GEMINI_API_KEY

Workflow steps

5 steps, taken from the step headings in SKILL.md.

  1. Detect Backend
  2. Write Prompt Files
  3. Select Script
  4. Generate
  5. Verify and Report

What it can do on your machine

Read from SKILL.md and the folder at commit 5218674. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Ships 4 files in scripts/ (Python), which the agent can run.

    Shell commands in SKILL.md call:

    • python3
    • pip

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md. Its commands use pip, which can reach the network depending on how they are called.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names these keys or tokens, usually read from environment variables:

    • GEMINI_API_KEY

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Image Gen loads about 1.3k tokens when it runs, and up to ~4k if it reads all its reference files. Until then it costs about 29 tokens; SKILL.md has 458 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~29
When it runs · the whole SKILL.md, loaded when a task matches
~1.3k
With references · SKILL.md plus every file in references/, read only if the agent opens them
~4k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); the scripts in this folder are not scanned.

SKILL.md

The full file from notque/vexjoy-agent at commit 5218674, republished under its MIT licence (© notque). 458 words, ~1,308 tokens.

Download SKILL.mdSave it as .claude/skills/image-gen/SKILL.md (or your agent's skills folder). This skill also uses 6 other files; get the full folder from GitHub.
name
image-gen
description
AI image generation: Gemini and Nano Banana backends; single/series/batch workflows with prompt-to-disk.
agent
python-general-engineer
user-invocable
false
routing.category
image-generation
routing.triggers
generate image, create image, image generation, AI image, gemini image, make image, draw, illustrate, sprite generation, card art, batch generation, series of…
routing.not_for
HTML visualization or charts (use html-artifact), or deterministic non-AI palette/matrix pixel art (use game-asset-generator)
routing.pairs_with
python-general-engineer, game-dev

image-gen

Backend-agnostic image generation: single images, series with anchor-chain consistency, batch pipelines. Two backends: Gemini (API) and Nano Banana (local scripts with post-processing).

Deep References

SignalLoadContent
Gemini backend selectedreferences/backends/gemini.mdModels, env vars, flag table, examples, error codes
Nano Banana needed (post-processing, series, JSON batch, style-match)references/backends/nano-banana.mdSubcommands, flags, aspect ratios, prompt patterns by asset type

Phase 1: Detect Backend

bash
python3 skills/content/image-gen/scripts/detect-backend.py
  • gemini -- load references/backends/gemini.md
  • ask -- no key found; ask the user to set GEMINI_API_KEY

Gate: backend confirmed.

Phase 2: Write Prompt Files

Write all prompts to disk before any API call. Prompt files are the generation record and anchor-chain input for series.

File naming: single prompts/YYYY-MM-DD-{slug}.md, series prompts/{series-name}-01.md through -NN.md.

markdown
---
model: gemini-3-pro-image-preview
aspect-ratio: 1:1
flags: []
---

Full prompt text. Be explicit about subject, style, background, constraints.
bash
mkdir -p prompts

For series: write ALL prompt files before calling any generation script.

Gate: all prompt files written and reviewed.

Phase 3: Select Script

Use caseScriptSubcommand
Single image, Geminiscripts/generate_image.py--prompt
Batch from text file, Geminiscripts/generate_image.py--batch
Single with post-processingscripts/nano-banana-generate.pygenerate
Style match from referencescripts/nano-banana-generate.pywith-reference
Batch from JSON manifestscripts/nano-banana-generate.pybatch
Series (anchor chain)scripts/nano-banana-generate.pygenerate then with-reference
Post-processing onlyscripts/nano-banana-process.pycrop / remove-bg / pipeline

Model selection:

ScenarioModel
Draft, testing, batch, cost-sensitivegemini-2.5-flash-image (2-5s)
Final asset, character art, typographygemini-3-pro-image-preview (~30s)

Aspect ratio by use case:

Asset typeRatio
Sprites, characters, icons1:1
Card art, landscape16:9
Vertical maps, portrait bg9:16
Portrait cards3:4
Wide banners21:9

Generate at the target ratio. Generating 1:1 and cropping to 16:9 loses 56% of pixels.

Gate: script and subcommand identified.

Phase 4: Generate

Use absolute paths for output files. Show full script output.

Show full SKILL.md (202 more words)Show less
Anchor-Chain Algorithm (Series)

Character drift occurs when images are generated independently. Prevent it by passing the previous output as --reference:

image-01.png (no ref) -> image-02.png (ref=01) -> image-03.png (ref=02) -> ...
  1. Generate image 1 with no reference.
  2. Use output of image 1 as --reference for image 2.
  3. Continue: each image N references image N-1.

Save originals with --save-original for any batch or expensive generation. Re-processing a saved original is free; re-generating costs quota and may break the chain.

Gate: script exits 0.

Phase 5: Verify and Report

Read the generated image to verify:

  • Subject matches prompt
  • No unwanted watermarks or artifacts
  • Aspect ratio and framing correct
  • No excessive padding or dark borders

If inspection fails: regenerate with adjusted prompt. Report the issue before retrying.

Report: output file path (absolute), dimensions, model, post-processing applied, verification result. Report only what was requested.

Error Handling

ErrorCauseResolution
GEMINI_API_KEY not setMissing env varexport GEMINI_API_KEY=your_key
No image in responseSafety filter or text-only responseAdjust prompt; remove policy-adjacent content
Missing dependency: google-genaiPackage absentpip install google-genai pillow
Rate limit exceeded (429)Too many requestsIncrease --delay; script retries automatically
Content policy violation (400)Restricted contentRephrase using neutral language
Model not foundWrong model stringUse exact strings: gemini-2.5-flash-image or gemini-3-pro-image-preview

© notque, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 6 other files (scripts, references) in skills/content/image-gen of notque/vexjoy-agent.

  • SKILL.md
  • references/backends/gemini.md
  • references/backends/nano-banana.md
  • scripts/detect-backend.py
  • scripts/generate_image.py
  • scripts/nano-banana-generate.py
  • scripts/nano-banana-process.py

Open the folder on GitHubat commit 5218674

Compare with similar skills

Image Gen next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Image Gen compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Image Gen this skillnotque/vexjoy-agent435—~1.3kAutomated safety check: PassMIT
AI Image Generation and Editingzhayujie/CowAgent47k—~1.3kAutomated safety check: PassMIT
Gemini Web Reverse-Engineered ClientJimLiu/baoyu-skills26k6 repos~1.6kAutomated safety check: PassMIT
Logo Generatorop7418/logo-generator-skill2.2k—~1.8kAutomated safety check: NotesNone
NanobananaReScienceLab/opc-skills1.8k1 repos~1.3kAutomated safety check: PassApache-2.0
SEO Image GeneratorAgriciDaniel/claude-seo18k2 repos~2.1kAutomated safety check: PassMIT

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Works with

Questions about Image Gen

What does Image Gen do?

AI image generation: Gemini and Nano Banana backends; single/series/batch workflows with prompt-to-disk. Image Gen is an agent skill from notque/vexjoy-agent. AI image generation: Gemini and Nano Banana backends; single/series/batch workflows with prompt-to-disk.

When should I use Image Gen?

Image Gen fits situations like: tasks that involve Image generation.

How do I install Image Gen in Claude Code?

Run `npx skills add notque/vexjoy-agent --skill image-gen -a claude-code`. Or copy the skill folder (skills/content/image-gen in notque/vexjoy-agent) into .claude/skills/image-gen in your project. Claude Code loads it when a task matches its description.

How do I install Image Gen in Codex?

Run `npx skills add notque/vexjoy-agent --skill image-gen -a codex`. Or copy the skill folder (skills/content/image-gen in notque/vexjoy-agent) into .agents/skills/image-gen in your project. Codex loads it when a task matches its description.

Can I use Image Gen in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add notque/vexjoy-agent --skill image-gen -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/image-gen, .gemini/skills/image-gen, .github/skills/image-gen and .opencode/skills/image-gen in your project.

What does Image Gen need to run?

Going by SKILL.md and its folder, Image Gen needs Python for the scripts in its folder, the command-line tools its instructions call (python3 and pip) and credentials named GEMINI_API_KEY. Our summary lists: Python 3; A credential in GEMINI_API_KEY.

Does Image Gen access the network?

SKILL.md contains no URLs. Its commands use pip, which can reach the network depending on how they are called. This is read from the text; nothing was executed.

Is Image Gen safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. The check reads SKILL.md only: the scripts in the folder are not scanned, so read them before running anything.

What licence does Image Gen use?

Image Gen is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Image Gen use?

About 1.3k tokens (SKILL.md is roughly 5.2k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 2.7k tokens, read only when the agent opens those files.

What are the alternatives to Image Gen?

Skills that share tags, products or a category with Image Gen: AI Image Generation and Editing (zhayujie/CowAgent, 47k stars), Gemini Web Reverse-Engineered Client (JimLiu/baoyu-skills, 26k stars), Logo Generator (op7418/logo-generator-skill, 2.2k stars) and Nanobanana (ReScienceLab/opc-skills, 1.8k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Image Gen?

notque (a GitHub user) maintains it in notque/vexjoy-agent, which has 435 GitHub stars. The repository holds 61 skills in this directory. The repository was last updated on October 3, 2026.

Source: notque/vexjoy-agent on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.