DAY 0 Support: Gemini 3.1 Flash Lite Preview on LiteLLM

LiteLLM now supports gemini-3.1-flash-lite-preview with full day 0 support!

note

If you only want cost tracking, you need no change in your current Litellm version. But if you want the support for new features introduced along with it like thinking levels, you will need to use v1.80.8-stable.1 or above.

Deploy this version

Docker

docker run litellm

docker run \
-e STORE_MODEL_IN_DB=True \
-p 4000:4000 \
ghcr.io/berriai/litellm:main-v1.80.8-stable.1

Pip

pip install litellm

pip install litellm==v1.80.8-stable.1

What's New

Supports all four thinking levels:

• MINIMAL: Ultra-fast responses with minimal reasoning
• LOW: Simple instruction following
• MEDIUM: Balanced reasoning for complex tasks
• HIGH: Maximum reasoning depth (dynamic)

---

Quick Start

SDK

Basic Usage

from litellm import completion

response = completion(
    model="gemini/gemini-3.1-flash-lite-preview",
    messages=[{"role": "user", "content": "Extract key entities from this text: ..."}],
)

print(response.choices[0].message.content)

With Thinking Levels

from litellm import completion

# Use MEDIUM thinking for complex reasoning tasks
response = completion(
    model="gemini/gemini-3.1-flash-lite-preview",
    messages=[{"role": "user", "content": "Analyze this dataset and identify patterns"}],
    reasoning_effort="medium",  # low, medium , high
)

print(response.choices[0].message.content)

PROXY

1. Setup config.yaml

model_list:
  - model_name: gemini-3.1-flash-lite
    litellm_params:
      model: gemini/gemini-3.1-flash-lite-preview
      api_key: os.environ/GEMINI_API_KEY
  
  # Or use Vertex AI
  - model_name: vertex-gemini-3.1-flash-lite
    litellm_params:
      model: vertex_ai/gemini-3.1-flash-lite-preview
      vertex_project: your-project-id
      vertex_location: us-central1

2. Start proxy

litellm --config /path/to/config.yaml

3. Make requests

curl -X POST http://localhost:4000/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer <YOUR-LITELLM-KEY>" \
  -d '{
    "model": "gemini-3.1-flash-lite",
    "messages": [{"role": "user", "content": "Extract structured data from this text"}],
    "reasoning_effort": "low"
  }'

---

Supported Endpoints

LiteLLM provides full end-to-end support for Gemini 3.1 Flash Lite Preview on:

• ✅ /v1/chat/completions - OpenAI-compatible chat completions endpoint
• ✅ /v1/responses - OpenAI Responses API endpoint (streaming and non-streaming)
• ✅ /v1/messages - Anthropic-compatible messages endpoint
• ✅ /v1/generateContent – Google Gemini API compatible endpoint

All endpoints support:

• Streaming and non-streaming responses
• Function calling with thought signatures
• Multi-turn conversations
• All Gemini 3-specific features (thinking levels, thought signatures)
• Full multimodal support (text, image, audio, video)

---

reasoning_effort Mapping for Gemini 3.1

LiteLLM automatically maps OpenAI's reasoning_effort parameter to Gemini's thinkingLevel:

reasoning_effort	thinking_level	Use Case
minimal	minimal	Ultra-fast responses, simple queries
low	low	Basic instruction following
medium	medium	Balanced reasoning for moderate complexity
high	high	Maximum reasoning depth, complex problems
disable	minimal	Disable extended reasoning
none	minimal	No extended reasoning