Function Calling

Gemini's ability to return structured calls to developer-declared functions/tools, enabling tool use and agentic workflows. · Official docs

Related concepts

• Getting Started · Gemini Capabilities · Prompt Engineering · Function Calling & Tools · Agents & ADK · Agent Engine · RAG & Grounding · Vertex AI Search · Vision · Audio & Speech · Multimodal Live API · Evaluation · Open & Partner Models · MLOps & Deployment · Applied Use Cases

Used in 60 notebooks

Agents & ADK (6)

• Getting Started with Bidirectional Streaming v2 on Agent Runtime — Builds and deploys Agent Runtime bidirectional streaming agents, including a Live API audio agent.
• Deploy your first agent to Vertex AI Agent Engine — Deploys ADK agents to Vertex AI Agent Engine with Express Mode, agent object, and inline source workflows.
• Get started with Agent Engine Terraform Deployment — Deploy Vertex AI Agent Engine agents with Terraform, cloudpickle packaging, and ADK tools.
• Get started with Code Execution on Vertex AI Agent Engine — Runs LLM-generated Python securely with Vertex AI Agent Engine Sandbox and ADK agents.
• Getting Started with Live API on Agent Engine — Deploys bidirectional streaming agents on Vertex AI Agent Engine using Gemini Live API audio and ADK tools.
• Intro to Managed Agents API on Agent Platform (cURL) — Shows how to manage and interact with Managed Agents on Agent Platform using REST and cURL.

Gemini (49)

• Vertex AI Agent Engine in Express Mode — Build, test, deploy, and query a Gemini ADK currency agent on Vertex AI Agent Engine Express Mode.
• Intro to Building and Deploying an Agent with Agent Engine in Vertex AI — Builds, tests, deploys, streams, customizes, and deletes a LangChain Gemini agent on Vertex AI Agent Engine.
• Persisting LangChain History with Vertex AI Session Service — Persists LangChain chat and tool history in Vertex AI Agent Engine Session Service.
• Building and Deploying a Human-in-the-Loop LangGraph Application with Agent Engine on Vertex AI — Builds, tests, deploys, and resumes a human-in-the-loop LangGraph agent on Vertex AI Agent Engine.
• Building and Deploying a Google Maps API Agent with Agent Engine — Builds, tests, deploys, and queries a Gemini Google Maps agent on Vertex AI Agent Engine.
• Building a Multi-Agent RAG Application with LangGraph and Agent Engine — Builds and deploys a LangGraph multi-agent RAG app on Vertex AI Agent Engine with Cloud SQL vector stores.
• Building a Conversational Search Agent with Agent Engine and RAG on Vertex AI Search — Builds and deploys a Gemini movie-search RAG agent with LangChain, Agent Engine, and Vertex AI Search.
• Function Calling Agent — Builds a Gemini function-calling retail assistant over Cymbal Retail data in BigQuery.
• Task Planner Agent — Builds a LangGraph task-planner agent that plans, searches with Gemini, reflects, and responds.
• Query a Remote LangGraph Agent Server — Queries a local or Cloud Run LangGraph RemoteGraph agent and displays streamed agent outputs and state.
• Using OpenAI libraries with Gemini on Vertex AI — Calls Gemini on Vertex AI through OpenAI Chat Completions with streaming, tools, schemas, caching, and safety.
• Intro to Generating and Executing Python Code with Gemini 3 — Uses Gemini 3.5 Flash code execution to generate, run, inspect, and stream Python results via Vertex AI.
• Intro to Computer Use with Gemini — Builds a Gemini Computer Use browser agent loop with Playwright and screenshots.
• Create a Gen AI Agent Evaluation for a Deployed Agent — Runs inference and creates a persisted Gen AI Agent Evaluation for a deployed Vertex AI agent.
• Evaluate Generative Model Tool Use — Evaluates Gemini function calling and saved tool-call predictions with Vertex AI EvalTask metrics.
• Evaluating Agents - Evaluate a CrewAI agent with Vertex AI Gen AI Evaluation Service — Evaluates a CrewAI product agent with Vertex AI Gen AI Evaluation metrics and BYOD evaluation data.
• Evaluating Agents - Evaluate a LangGraph agent with Vertex AI Gen AI Evaluation Service — Evaluates a LangGraph Gemini agent with Vertex AI Gen AI Evaluation metrics and BYOD data.
• Evaluate Generative Model Tool Use with Custom Code Execution — Evaluates Gemini tool-use outputs with Vertex AI remote custom metrics.
• Evaluate your ADK agent using Vertex AI Gen AI Evaluation service — Evaluates an ADK product research agent with Vertex AI Gen AI Evaluation metrics.
• Forced Function Calling with Tool Configurations in Gemini — Shows how to force, allow, or disable Gemini function calls with tool configurations.
• Working with Data Structures and Schemas in Gemini Function Calling — Shows how to extract structured function-call arguments from Gemini using simple, array, and nested schemas.
• Intro to Function Calling with the Gemini API & Python SDK — Introduces Gemini function calling in Vertex AI with chat tools, mock API responses, and live geocoding.
• Multimodal Function Calling with the Gemini API & Python SDK — Shows Gemini multimodal function calling with images, video, audio, PDFs, and chat using Google Gen AI SDK.
• Working with Parallel Function Calls and Multiple Function Responses in Gemini — Shows how Gemini returns and handles parallel function calls with Wikipedia lookup tools.
• Intro to Gemini 2.5 Flash — Introduces Gemini 2.5 Flash on Vertex AI with text, thinking, multimodal, tools, and structured output.
• Intro to Gemini 2.5 Pro — Introduces Gemini 2.5 Pro on Vertex AI using the Google Gen AI SDK for text, multimodal, tools, and reasoning.
• Intro to Gemini 3.1 Flash-Lite — Quickstart for Gemini 3.1 Flash-Lite with Google Gen AI SDK on Google Cloud.
• Intro to Gemini 3.1 Pro — Quickstart for Gemini 3.1 Pro on Vertex AI with Google Gen AI SDK API features.
• Intro to Gemini 3.5 Flash — Quickstart for Gemini 3.5 Flash generation, multimodal inputs, tools, grounding, and safety with Google GenAI SDK.
• Intro to Gemini 3 Flash (Preview) — Quickstart for Gemini 3 Flash Preview on Vertex AI with Gen AI SDK features and multimodal/tool examples.
• REST API — Uses cURL to call Gemini 3.5 Flash on Vertex AI for text, chat, tools, multimodal, and JSON output.
• Getting started with Gemini using Vertex AI in Express Mode — Introduces Gemini on Vertex AI Express Mode using the Google Gen AI SDK.
• Intro to Model Context Protocol (MCP) integration with Vertex AI — Shows how to connect Gemini on Vertex AI to custom and prebuilt MCP servers.
• Getting Started with Model Optimizer — Introduces Vertex AI Model Optimizer routing with Google Gen AI SDK prompts and function calls.
• Getting Started with Gemini Live API using WebSocket — Uses Gemini Live API over WebSocket for text, audio, video, tools, and native audio features.
• Getting Started with Gemini Live API using Gen AI SDK — Introduces Gemini Live API audio sessions, tools, transcription, and VAD with the Google Gen AI SDK.
• From API to Report: Building a Currency Analysis Agent with LangGraph and Gemini — Builds a LangGraph currency analysis agent using Gemini on Vertex AI and an exchange-rate API.
• Build Your Own AI Podcasting Agent with LangGraph, Gemini, and Chirp 3 — Builds a LangGraph podcast agent using Gemini research loops and Chirp 3 text-to-speech audio.
• Chain of Thought & ReAct — Demonstrates CoT prompting and ReAct agents with Vertex AI, LangChain, Wikipedia, and BigQuery.
• Get Started with Vertex AI Prompt Optimizer - Tool usage — Optimizes a Gemini tool-calling system instruction with Vertex AI Prompt Optimizer data-driven mode.
• Intro to thought signatures — Shows how Gemini thought signatures preserve reasoning context across multi-turn function calling.
• Intro to thought signatures with REST API — Shows how to pass Gemini thought signatures through REST function-calling turns.
• Analyze a codebase with Gemini in Vertex AI — Uses Gemini 3.5 Flash on Vertex AI to analyze, document, debug, and extend a GitHub codebase.
• Get hands-on with a customer support use case using Gemini and Gen AI SDK — Builds a Gemini customer-support flow for retail product matching, room-fit reasoning, tools, search, and Live API audio.
• GraphRAG on Google Cloud With Spanner and Vertex AI Agent Engine — Builds a GraphRAG Q&A agent with Spanner Graph, Gemini, ADK, and Vertex AI Agent Engine.
• ReAct (Reasoning + Acting) + Custom tool for Healthcare NL API + Gemini 2.0 + LangChain — Builds a LangChain ReAct agent using Gemini 2.0 and Healthcare NLP to suggest medical billing codes.
• Productivity Coaching with Gemini and Google Calendar — Uses Gemini 2.5 Flash with Google Calendar data to provide productivity coaching and schedule recommendations.
• Retail AI Location Strategy: Autonomous Site Selection & Market Analysis — Builds a Gemini 3 retail site-selection pipeline using search, Maps, code execution, reasoning, and JSON output.
• Building a Multimodal Chatbot for Warranty Claims using Gemini and Vector Search in Vertex AI — Builds a multimodal warranty-claims chatbot with Gemini, RAG, Vector Search, and function calling.

Open Models (3)

• Building an ADK agent using QWEN 3 on Vertex AI — Builds and deploys an ADK weather agent using Qwen3 on Vertex AI and Agent Engine.
• Serving Open-Source LLMs on Vertex AI with LiteLLM and OpenAI-Compatible APIs — Deploys a Llama 3.1 Model Garden model on Vertex AI and calls it through LiteLLM OpenAI-style APIs.
• Build and deploy a Hugging Face smolagent using DeepSeek-r1 on Vertex AI — Deploys DeepSeek R1 Distill Qwen 7B on Vertex AI and wraps it in a smolagents math verifier agent.

Partner Models (1)

• Multimodal Function Calling with Claude Models — Uses Claude on Vertex AI for multimodal prompting and tool use with a Wikipedia lookup.

SDK (1)

• Getting started with Google Generative AI using the Gen AI SDK — Introduces Google Gen AI SDK on Vertex AI for Gemini prompts, tools, caching, batches, and embeddings.

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