Google Gemini 3 API Adds Built-in Tools + Function Calling Combination and Maps Grounding
On March 18, 2026, the Gemini API changelog detailed the release of built-in tools and custom function calling combination support plus native Grounding with Google Maps for Gemini 3 models, allowing unified tool use in a single API call.
TLDR
Google released updates to the Gemini API on March 18, 2026, making it possible to use Gemini's built-in tools (such as Google Search and Maps) alongside developers' custom function calling tools within a single API call. Grounding with Google Maps became supported for Gemini 3 models to deliver more accurate location-aware responses.
Built-in Tools and Function Calling Combination
Previously, developers often had to orchestrate built-in tools and custom functions separately. The new combination feature allows both to be specified together in one generateContent request. This reduces complexity for agentic workflows that need both Google ecosystem capabilities (Search, file search, code execution) and arbitrary external or internal functions.
The release notes also reference improved context circulation when using built-in tools, helping the model retain relevant state across multi-step tool interactions.
Maps Grounding for Gemini 3
Grounding with Google Maps is now available for Gemini 3 models. When enabled, responses involving locations, directions, places, or geospatial data can be grounded directly against Google Maps data, providing citations and reducing fabricated details in location-sensitive outputs.
Supported models for the Maps grounding feature are documented in the Gemini API references.
Why this story matters
Reliable tool use and grounding are foundational for production agentic AI. By allowing seamless mixing of first-party and custom tools without extra orchestration layers, and adding real-world map data as a grounding source, Google is lowering the barrier for developers building location-aware, multi-tool agents on Gemini 3. These changes directly address common pain points in current tool-calling implementations.
Sources
- Google AI for Developers — Gemini API Release notes, March 18, 2026 entry: "Released the new Built-in Tools and Function Calling Combination feature..." and "Grounding with Google Maps is now supported for Gemini 3 models going forward."
- Additional developer discussions and Threads posts noting the March 18 rollout of tool combo and Maps grounding capabilities.