nanobanana-skill

nanobanana-skill is a skill for Codex from feiskyer/codex-settings. It costs 107 tokens per session (2,179 once invoked), scanned A, original, MIT.

A guide for creating and editing images with Nanobanana, using a bundled command-line tool and Gemini image models. It includes text-based generation, image editing, reference-image composition, and style changes.

In plain words
What is it for?
Use it to generate new images, edit existing ones, combine reference images, create marketing graphics, or make visuals that need web-grounded information.
Why use it?
It explains when this image tool is appropriate and what setup it needs. This reduces uncertainty when an image task requires references, accurate text, or current web information.

Skill for Codex

Written for Codex: agents/openai.yaml present. Also seen: mentions Gemini CLI.

Good fit Use it to generate new images, edit existing ones, combine reference images, create marketing graphics, or make visuals that need web-grounded information.

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Install with agentmods
npx agentmods add skills/feiskyer/codex-settings/nanobanana-skill
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.

Any agent
npx skills add feiskyer/codex-settings --skill nanobanana-skill
Clone the repo
git clone --depth 1 https://github.com/feiskyer/codex-settings

Made for: Codex.

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 nanobanana-skill

README.md
[![agentmods](https://agentmods.dev/badge/skills/feiskyer/codex-settings/nanobanana-skill/github.svg)](https://agentmods.dev/skills/feiskyer/codex-settings/nanobanana-skill)
Your own site
<a href="https://agentmods.dev/skills/feiskyer/codex-settings/nanobanana-skill"><img src="https://agentmods.dev/badge/skills/feiskyer/codex-settings/nanobanana-skill/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for nanobanana-skill

Your own site · 80×15
<a href="https://agentmods.dev/skills/feiskyer/codex-settings/nanobanana-skill"><img src="https://agentmods.dev/badge/skills/feiskyer/codex-settings/nanobanana-skill.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 107 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,179 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 1 finding, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium Rogue Agent · line 79
    Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.
    Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
How audits are shown
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 5.1 $0.00107 $0.02179
Opus 5 $0.00053 $0.01090
Sonnet 5 $0.00021 $0.00436
Haiku 4.5 $0.00011 $0.00218

Measured 9d ago against content hash 0b4870a685e1, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

nanobanana-skill 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 9d ago.

The scan reads SKILL.md. This mod also ships 2 executable files (nanobanana.py, tests/test_nanobanana.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

skills/nanobanana-skill/SKILL.md · 241 lines

How it starts

The opening of the file, as written. The whole thing — 241 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Nanobanana Image Skill

Use the bundled nanobanana.py tool to generate or edit images with Gemini image models. The default path now targets Nano Banana 2 (gemini-3.1-flash-image-preview) and turns on thinking summaries plus Google Search grounding by default, because those defaults are the main reason to use this skill instead of a generic image prompt.

When to use this skill

Use it for:

  1. Creating a new image from text
  2. Editing or remixing one or more existing images
  3. Combining several reference images into one composition
  4. Requests where factual freshness matters and image grounding should use live web data
  5. Requests that need strong text rendering, layout reasoning, or more deliberate composition

Do not use it for:

  1. Non-image tasks
  2. Image work that explicitly must use another provider or another installed image skill

Requirements

  1. GEMINI_API_KEY must exist in ~/.nanobanana.env or the shell environment.
  2. Python dependencies from requirements.txt must be installed.
  3. The executable is the nanobanana.py file in this same skill directory. Resolve its absolute path once before running it.

The CLI can display --help without credentials. It validates local input files before creating an API client and exits non-zero when the API returns no image.

Example env file:

GEMINI_API_KEY=sk-dummy

Default behavior

Unless the user explicitly asks otherwise, prefer these defaults:

  1. Model: gemini-3.1-flash-image-preview
  2. Search grounding: enabled
  3. Thinking summaries: enabled
  4. Thinking level: high
  5. Resolution: 1K
  6. Aspect ratio: leave unspecified unless the user clearly wants a shape

Leaving aspect ratio unspecified is usually better for edits because Gemini can match the input image shape. For text-only generation, pick an aspect ratio only when the user implies a format such as poster, square post, banner, phone wallpaper, or ultrawide hero image.

Workflow

1. Clarify only the missing constraints

Read the full file on GitHub · 241 lines

Files

What ships with it

4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 9d ago First seen · 241 lines · 107 tokens per session scan A 0b4870a685e1

Subscribe to this mod's changes

nanobanana-skill is a skill published in the GitHub repository feiskyer/codex-settings (236 stars, last pushed 26d ago), licensed MIT. It adds 107 tokens to every session and 2,179 once invoked, about $0.0005 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.

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