GCP Gemini API Developer

Build, integrate, and debug Gemini API applications on Google Cloud Agent Platform (formerly Vertex AI) using the unified google-genai SDK. Covers text generation, multimodal inputs, function calling, structured output, embeddings, context caching, batch prediction, streaming, Live API (bidirectional voice/video), and model tuning across Python, TypeScript/JavaScript, Go, Java, and C#. Use when building Gemini-powered applications, migrating from deprecated Vertex AI or google-generativeai SDKs, or integrating Gemini capabilities into a GCP-hosted service.

VincentChuWaiChow 3299cf1 2 files · 5.9 KB Updated Sep 17, 2026

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GCP Gemini API Developer

IMPORTANT BRANDING NOTE

"Agent Platform" (full name: Gemini Enterprise Agent Platform) was previously named "Vertex AI". Many web resources still use "Vertex AI" branding.

CRITICAL SDK NOTE

The following SDKs are DEPRECATED and must NOT be used:

google-cloud-aiplatform (Python)
@google-cloud/vertexai (Node.js)
google-generativeai (Python — Gemini Developer API SDK)

Use ONLY the unified Gen AI SDK:

Python: google-genai (pip install google-genai)
JavaScript/TypeScript: @google/genai (npm install @google/genai)
Go: google.golang.org/genai (go get google.golang.org/genai)
Java: com.google.genai:google-genai
C#/.NET: Google.GenAI (dotnet add package Google.GenAI)

Authentication

# Application Default Credentials (ADC) — preferred
export GOOGLE_CLOUD_PROJECT='your-project-id'
export GOOGLE_CLOUD_LOCATION='global'  # Use 'global' for automatic region routing
export GOOGLE_GENAI_USE_VERTEXAI=true

Model Selection

gemini-3.1-pro-preview — complex reasoning, coding, research (1M tokens)
gemini-3-flash-preview — fast, balanced, multimodal (1M tokens)
gemini-3.1-flash-lite-preview — high-frequency lightweight tasks
gemini-3-pro-image-preview — image generation and editing
gemini-live-2.5-flash-native-audio — Live Realtime API (bidirectional audio/video)
DEPRECATED (do not use): gemini-2.0-, gemini-1.5-, gemini-1.0-*, gemini-pro

Quick Start (Python)

from google import genai
client = genai.Client  # picks up env vars automatically
response = client.models.generate_content(
    model="gemini-3-flash-preview",
    contents="Explain transformer architecture"
)
print(response.text)

Reference Directory

Load only when needed:

Scenario	Trigger Keywords	Reference
Text + multimodal	chat, image, video, audio, streaming	references/text-multimodal.md
Function calling + tools	tool use, function call, grounding, code execution	references/tools.md
Structured output	JSON, schema, structured, typed response	references/structured-output.md
Embeddings	embedding, semantic search, vector	references/embeddings.md
Context caching	cache, large context, caching tokens	references/caching.md
Batch prediction	batch, async, large dataset	references/batch.md
Live API	live, realtime, voice, video streaming, bidirectional	references/live-api.md
Model tuning	fine-tune, SFT, preference tuning	references/tuning.md
Safety	safety filter, threshold, harm category	references/safety.md
SDK migration	migrate, deprecated, upgrade	references/migration.md

Core Rules

ALWAYS use the unified google-genai SDK family. If user code imports google-cloud-aiplatform, @google-cloud/vertexai, or google-generativeai, flag it as deprecated and provide migration guidance.
Use location="global" (global endpoint) by default for automatic capacity routing. Only use a specific region if the user explicitly requests it.
Initialize the client without parameters when environment variables are set — don't hardcode project/location in code.
gemini-3.1-pro-preview ≠ gemini-3-pro-preview — the latter does NOT exist; use the correct model IDs.
Context caching (CachedContent) reduces cost for repeated large contexts (system prompts, documents) — recommend it proactively for production workloads with stable large contexts.
For production, consult docs for stable model version aliases rather than using -preview models.
Batch prediction (BatchJob) is for async large-dataset inference — use it instead of looping generate_content for bulk processing.

Official Docs

Security Notes

Read-only advisory. Never embed API keys or service account credentials in code examples. Use ADC and environment variables. Do not call batch jobs or fine-tuning jobs on production data without explicit user approval.

---name: gcp-gemini-api-developerdescription: Build, integrate, and debug Gemini API applications on Google Cloud Agent Platform (formerly Vertex AI) using the unified google-genai SDK. Covers text generation, multimodal inputs, function calling, structured output, embeddings, context caching, batch prediction, streaming, Live API (bidirectional voice/video), and model tuning across Python, TypeScript/JavaScript, Go, Java, and C#. Use when building Gemini-powered applications, migrating from deprecated Vertex AI or google-generativeai SDKs, or integrating Gemini capabilities into a GCP-hosted service.---# GCP Gemini API Developer## IMPORTANT BRANDING NOTE"Agent Platform" (full name: Gemini Enterprise Agent Platform) was previously named "Vertex AI". Many web resources still use "Vertex AI" branding.## CRITICAL SDK NOTEThe following SDKs are DEPRECATED and must NOT be used:- `google-cloud-aiplatform` (Python)- `@google-cloud/vertexai` (Node.js)- `google-generativeai` (Python — Gemini Developer API SDK)Use ONLY the unified Gen AI SDK:- Python: `google-genai` (`pip install google-genai`)- JavaScript/TypeScript: `@google/genai` (`npm install @google/genai`)- Go: `google.golang.org/genai` (`go get google.golang.org/genai`)- Java: `com.google.genai:google-genai`- C#/.NET: `Google.GenAI` (`dotnet add package Google.GenAI`)## Authentication```bash# Application Default Credentials (ADC) — preferredexport GOOGLE_CLOUD_PROJECT='your-project-id'export GOOGLE_CLOUD_LOCATION='global' # Use 'global' for automatic region routingexport GOOGLE_GENAI_USE_VERTEXAI=true```## Model Selection- `gemini-3.1-pro-preview` — complex reasoning, coding, research (1M tokens)- `gemini-3-flash-preview` — fast, balanced, multimodal (1M tokens)- `gemini-3.1-flash-lite-preview` — high-frequency lightweight tasks- `gemini-3-pro-image-preview` — image generation and editing- `gemini-live-2.5-flash-native-audio` — Live Realtime API (bidirectional audio/video)- DEPRECATED (do not use): gemini-2.0-*, gemini-1.5-*, gemini-1.0-*, gemini-pro## Quick Start (Python)```pythonfrom google import genaiclient = genai.Client # picks up env vars automaticallyresponse = client.models.generate_content( model="gemini-3-flash-preview", contents="Explain transformer architecture")print(response.text)```## Reference DirectoryLoad only when needed:| Scenario | Trigger Keywords | Reference ||---|---|---|| Text + multimodal | chat, image, video, audio, streaming | references/text-multimodal.md || Function calling + tools | tool use, function call, grounding, code execution | references/tools.md || Structured output | JSON, schema, structured, typed response | references/structured-output.md || Embeddings | embedding, semantic search, vector | references/embeddings.md || Context caching | cache, large context, caching tokens | references/caching.md || Batch prediction | batch, async, large dataset | references/batch.md || Live API | live, realtime, voice, video streaming, bidirectional | references/live-api.md || Model tuning | fine-tune, SFT, preference tuning | references/tuning.md || Safety | safety filter, threshold, harm category | references/safety.md || SDK migration | migrate, deprecated, upgrade | references/migration.md |## Core Rules- ALWAYS use the unified `google-genai` SDK family. If user code imports `google-cloud-aiplatform`, `@google-cloud/vertexai`, or `google-generativeai`, flag it as deprecated and provide migration guidance.- Use `location="global"` (global endpoint) by default for automatic capacity routing. Only use a specific region if the user explicitly requests it.- Initialize the client without parameters when environment variables are set — don't hardcode project/location in code.- `gemini-3.1-pro-preview` ≠ `gemini-3-pro-preview` — the latter does NOT exist; use the correct model IDs.- Context caching (`CachedContent`) reduces cost for repeated large contexts (system prompts, documents) — recommend it proactively for production workloads with stable large contexts.- For production, consult docs for stable model version aliases rather than using `-preview` models.- Batch prediction (`BatchJob`) is for async large-dataset inference — use it instead of looping `generate_content` for bulk processing.## Official Docs- https://cloud.google.com/vertex-ai/generative-ai/docs/overview- https://cloud.google.com/vertex-ai/generative-ai/docs/sdks/overview- https://cloud.google.com/vertex-ai/generative-ai/docs/context-cache/context-cache-overview## Security NotesRead-only advisory. Never embed API keys or service account credentials in code examples. Use ADC and environment variables. Do not call batch jobs or fine-tuning jobs on production data without explicit user approval.

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