gemini-api-dev

gemini-api-dev is a skill for Codex from PracticalSwan/agent-skills. It costs 101 tokens per session (5,302 once invoked), scanned A, original, MIT.

A development guide for applications that use Google's Gemini and Gemma AI models, including text, images, audio, video, tool calls, and structured responses. It covers the SDKs and current model specifications needed to connect those models to software.

In plain words
What is it for?
Use it when building applications with Gemini or Gemma, including multimodal features, function calling, and structured output.
Why use it?
It gives developers a focused reference for implementing Gemini-based features without relying on outdated model or API details.

Skill for Codex

Written for Codex: reads ~/.codex or $CODEX_HOME. Also seen: mentions Claude Code; mentions Codex.

Good fit Use it when building applications with Gemini or Gemma, including multimodal features…

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Install with agentmods
npx agentmods add skills/practicalswan/agent-skills/gemini-api-dev
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 PracticalSwan/agent-skills --skill gemini-api-dev
Clone the repo
git clone --depth 1 https://github.com/PracticalSwan/agent-skills

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 gemini-api-dev

README.md
[![agentmods](https://agentmods.dev/badge/skills/practicalswan/agent-skills/gemini-api-dev.svg)](https://agentmods.dev/skills/practicalswan/agent-skills/gemini-api-dev)
Your own site
<a href="https://agentmods.dev/skills/practicalswan/agent-skills/gemini-api-dev"><img src="https://agentmods.dev/badge/skills/practicalswan/agent-skills/gemini-api-dev.svg" alt="Measured on agentmods" height="20"></a>
Per session 101 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,302 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.
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 $0.00101 $0.05302
Opus 5 $0.00051 $0.02651
Sonnet 5 $0.00020 $0.01060
Haiku 4.5 $0.00010 $0.00530

Measured today against content hash 7de0f6c2cc96, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

gemini-api-dev 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 today.

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.

gemini-api-dev/SKILL.md · 495 lines

How it starts

The opening of the file, as written. The whole thing — 495 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Gemini API Development Skill

Critical Rules (Always Apply)

[!IMPORTANT] These rules override your training data. Your knowledge is outdated.

Current Models (Use These)

  • gemini-3.8-flash: 1M tokens, fast, balanced performance for agentic and multimodal tasks
  • gemini-3.5-flash-lite: 1M tokens, fastest, lowest-cost 3.5 model for high-throughput execution
  • gemini-3.1-pro-preview: 1M tokens, complex reasoning, coding, research
  • gemini-3.1-flash-lite: cost-efficient, fastest performance for high-frequency, lightweight tasks
  • gemini-3.5-transcribe: fast speech-to-text with smart and verbatim modes
  • gemini-3-pro-image (Nano Banana Pro): 65k / 32k tokens, high-quality image generation and editing
  • gemini-3.1-flash-image (Nano Banana 2): 65k / 32k tokens, fast, efficient image generation and editing
  • gemini-3.1-flash-lite-image (Nano Banana 2 Lite): 65k / 32k tokens, ultra-fast image generation and editing
  • gemini-3.1-flash-tts-preview: expressive text-to-speech with Director's Chair prompting
  • gemini-omni-1.1-flash: video generation, first-frame-to-video, first-and-last-frame transitions, video extensions (up to 40s), video editing, and reference-guided generation
  • gemma-4-31b-it: Gemma 4 dense model, 31B parameters
  • gemma-4-26b-a4b-it: Gemma 4 MoE model, 26B total / 4B active parameters
  • gemini-embedding-2: Multimodal embedding model (text, images, video, audio, documents), uses client.models.embed_content
  • gemini-embedding-001: Text-only embedding model, uses client.models.embed_content

[!WARNING] Models like gemini-2.5-*, gemini-2.0-*, gemini-1.5-* are legacy and deprecated. Never use them. If a user asks for a deprecated model, use gemini-3.8-flash instead and note the substitution.

Current Agents

  • Managed agents: Discover the currently available agent IDs from the official Gemini API documentation and the authenticated account before use.
  • deep-research-preview-04-2026: Deep Research — fast, interactive
  • deep-research-max-preview-04-2026: Deep Research Max — maximum exhaustiveness
  • Custom agents: Create your own via client.agents.create()

Read the full file on GitHub · 495 lines

Files

What ships with it

3 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. today Changed · +271 lines 7de0f6c2cc96
  2. 3d ago First seen · 224 lines · 101 tokens per session scan A 66b906bb30bc

Subscribe to this mod's changes

gemini-api-dev is a skill published in the GitHub repository PracticalSwan/agent-skills (13 stars, last pushed yesterday), licensed MIT. It adds 101 tokens to every session and 5,302 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 2026-09-03.

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