DAY 0 Support: Gemini 3.1 Pro on LiteLLM

LiteLLM now supports gemini-3.1-pro-preview and all the new API changes along with it.

Deploy this version

Docker

docker run litellm

docker run \
-e STORE_MODEL_IN_DB=True \
-p 4000:4000 \
ghcr.io/berriai/litellm:main-v1.81.9-stable.gemini.3.1-pro

Pip

pip install litellm

pip install litellm==v1.81.9-stable.gemini.3.1-pro

What's New

1. New Thinking Levels: thinkingLevel with MINIMAL & MEDIUM

Gemini 3.1 Pro introduces support for medium thinking level

LiteLLM automatically maps the OpenAI reasoning_effort parameter to Gemini's thinkingLevel, so you can use familiar reasoning_effort values (minimal, low, medium, high) without changing your code!

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Supported Endpoints

LiteLLM provides full end-to-end support for Gemini 3.1 Pro 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
• Conversion of provider specific thinking related param to thinkingLevel

Quick Start

SDK

Basic Usage with MEDIUM thinking (NEW)

from litellm import completion

# No need to make any changes to your code as we map openai reasoning param to thinkingLevel
response = completion(
    model="gemini/gemini-3.1-pro-preview",
    messages=[{"role": "user", "content": "Solve this complex math problem: 25 * 4 + 10"}],
    reasoning_effort="medium",  # NEW: MEDIUM thinking level
)

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

PROXY

1. Setup config.yaml

model_list:
  - model_name: gemini-3.1-pro-preview
    litellm_params:
      model: gemini/gemini-3.1-pro-preview
      api_key: os.environ/GEMINI_API_KEY
  - model_name: vertex-gemini-3.1-pro-preview
    litellm_params:
      model: vertex_ai/gemini-3.1-pro-preview

2. Start proxy

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

3. Call with MEDIUM thinking

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-pro-preview",
    "messages": [{"role": "user", "content": "Complex reasoning task"}],
    "reasoning_effort": "medium"
  }'

---

reasoning_effort Mapping for Gemini 3+

reasoning_effort	thinking_level
minimal	minimal
low	low
medium	medium
high	high
disable	minimal
none	minimal