/google-genai-sdk-python

Reasoning (Thinking)

Reasoning models generate "thoughts" before the final response to improve accuracy on complex tasks.

Configuration

Gemini 3 Series

Use thinking_level to control reasoning depth.

• MINIMAL: Minimal reasoning, lowest latency.
• LOW: Simple tasks.
• MEDIUM: Balanced.
• HIGH: Maximum depth (default).

config = types.GenerateContentConfig(
    thinking_config=types.ThinkingConfig(
        thinking_level=types.ThinkingLevel.HIGH,
        include_thoughts=True # Returns thoughts in response
    )
)

Gemini 2.5 Series

Use thinking_budget (token count).

• 0: Thinking OFF.
• 1024: Specific token budget.

config = types.GenerateContentConfig(
    thinking_config=types.ThinkingConfig(
        thinking_budget=1024,
        include_thoughts=True
    )
)

Accessing Thoughts

If include_thoughts=True, thoughts are returned as parts.

for part in response.candidates[0].content.parts:
    if part.thought:
        print(f"Thought: {part.text}")
    else:
        print(f"Response: {part.text}")

Thought Signatures

When using tools with reasoning models, the API returns an encrypted thought_signature.

• Automatic: The SDK handles this automatically when using chats or preserving the full response object in history.
• Manual: If manually constructing history, you must include the thought_signature from the model's turn in the next request to avoid errors.