Gemini Decisions API: Fast, calibrated multimodal decisions
Google has launched the Gemini Decisions API, a new endpoint for quick, closed-set decisions powered by the Gemini Decision 1 model.
The tool offers built-in functions for bounded choices such as tool selection, policy checks, model routing, and context grading. Users can send one multimodal input covering text, images, audio, video, and PDFs (up to 256K tokens) alongside up to 1,000 independent questions. Instead of generating answer text token by token, Gemini Decision 1 scores candidate options in a single forward pass. This returns probabilities and confidence scores within 150-250 ms end-to-end latency at $0.10 per 1M input tokens with zero output tokens billed.
Strong performance and calibration
Gemini Decision 1 leads across benchmarks for agent routing, reasoning, ranking, and multimodal understanding, with the lowest calibration error.
The model scores options without token-by-token decoding. This keeps median latency at 50-100 ms of model compute (150-250 ms end-to-end) across multimodal inputs and contexts up to 16K tokens. Latency remains nearly flat from 1 to 100 questions per request. With zero output tokens billed, Gemini Decision 1 with the Decisions API is nearly 5x cheaper across the shared benchmark suite than Gemini 3.5 Flash-Lite with the Interactions API.
Native multimodal evaluation across three decision types in one pass
Built on Gemini’s native multimodal architecture, Gemini Decision 1 can process text, images, audio, video, and PDFs directly in a single forward pass. Users can combine modalities in one shared input, such as pairing a call recording with account metadata or a scanned PDF claim with damage photos. Resolution on image and video inputs can be tuned to control visual detail and token cost.
Multiple questions can be evaluated against that shared input in a single request, mixing yes/no checks, multiple choice, and rubric scores. Every answer includes a confidence score (from 0 to 1) so code can route ambiguous cases to a fallback or human reviewer:
- noul (Yes/No): Estimates the probability that a yes/no condition holds, with optional true and false description criteria.
- choice (Multiple Choice): Selects from 2 to 255 choices, returning the winner and normalized probabilities for every candidate.
- score (Ordered Rubric): Grades inputs across an ordered rubric (starting at 0), returning a continuous weighted score and per-level probabilities.
The
input
field uses the same
Content
block format as the Interactions API. The following example checks a photo of a breakroom counter, together with a text note, against all three question types in one request:
from google import genai client = genai.Client(http_options={"api_version": "v1beta"}) result = client.decisions.create( model="gemini-decision-1", input=[{ "type": "image", "uri": "https://storage.googleapis.com/generativeai-downloads/images/spill.jpg", "mime_type": "image/jpeg", }, { "type": "text", "text": "Breakroom counter check before the 9 AM client meeting.", }, ], questions={ "has_spill": { "type": "noul", "instructions": "Is there an uncleaned liquid spill on the counter?", }, "next_action": { "type": "choice", "instructions": "Which cleanup action fits the scene?", "criteria": { "wipe_with_cloth": "Small counter spill with a cloth or towel already nearby.", "dispatch_janitorial": "Large floor hazard, broken glass, or active leak.", "ready_for_meeting": "Counter is clean and ready.", }, }, "severity": { "type": "score", "instructions": "Rate the severity of the counter mess.", "criteria": [ "Clean and ready.", "Minor localized spill.", "Major spill or safety hazard.", ], }, }, )How teams are building with the Decisions API
Teams across Google are already using the Decisions API as a low-latency control plane. Features ship simply by defining options rather than training custom classifiers or waiting on generative calls:
- Dynamic model routing in Gemini Notebook: Gemini Notebook uses the Decisions API as a real-time router to instantly direct incoming queries to the optimal model tier and thinking level for each request. The Decisions API classifies intent in milliseconds to serve everyday queries with up to 40% lower latency while reserving deep reasoning models for complex tasks.
- Rapid design iteration in Stitch: The new rapid canvas experiment in Stitch uses the Decisions API to generate playable wireframes of a product flow in seconds and to apply edits made by voice or tap almost instantly. When the flow feels right, one click hands the screens off to the full Stitch experience for deeper design polish.
- Emoji selection in CC: CC from Google Labs uses the Decisions API to pick the right emoji reaction from a palette of more than 200 options in a fraction of a second, so reactions appear instantly without adding latency.
- Safety layer for MCP tools in Search: Google Search uses the Decision API to detect adversarial behavior and content against adversarial evals with high efficacy within the latency envelope.
Stitch Rapid uses the Decisions API to design an entire product flow in seconds (1x speed).
Start building today
Gemini Decision 1 is priced at $0.10 per 1M input tokens and $0 for output tokens. An API no-cost tier is available in Google AI Studio for prototyping. Your shared
input
is billed once per request no matter how many questions you evaluate (each question adds only its own instruction and criteria tokens). There are no output-token charges, variable thinking-token bills, or separate audio transcription and OCR costs.
Users can start building today by grabbing an API key in Google AI Studio, trying the Doorstep Parcels, Speed Sketch, and Find the Zoo Keeper demo apps, and following the Python, JavaScript, and REST guides in the Decisions API documentation.
Ecosystem integrations are rolling out across OpenRouter, LangChain, Vercel, LiteLLM, Pydantic AI, Pipecat, LiveKit, and OpenCode alongside the
google-genai
SDKs, with support coming soon to Gemini in Google Cloud.
