Gemini Models Guide

Model Overview

Gemini is Google’s latest generation of multimodal large language models, featuring long context windows and powerful multimodal understanding capabilities. From the latest Gemini 3.1 Pro Preview to the stable Gemini 2.5 Pro and fast Gemini 2.5 Flash, Gemini models excel in long document analysis, complex reasoning, code generation, and more.

OpenAI Format Compatible: Fully compatible with OpenAI API format, seamlessly integrate with your existing code

Model Classification

Gemini 3.1 / 2.5 Series

Gemini 3.1 Pro Preview

Latest Pro preview model for tools, multimodal input, and long-context tasks

Core Features:
- 1M tokens context window
- Strong tool and agent workflow support
- Powerful multimodal understanding
- Excellent reasoning capabilities
- Recommended for testing the latest Gemini capabilities
Pricing:
- Check the console for real-time pricing
Suitable Scenarios:
- Agent workflows
- Complex reasoning
- Multimodal analysis
- Long-context tasks

Gemini 2.5 Pro

Stable high-performance model with ultra-long context window

Core Features:
- 2M tokens context window (industry-leading)
- Powerful multimodal understanding
- Excellent reasoning capabilities
- Supports text, images, audio, and video
- Precise long document analysis
Pricing:
- Check the console for real-time pricing
Suitable Scenarios:
- Ultra-long document analysis
- Complex code repository understanding
- Multi-video content analysis
- Large-scale data processing
- Academic research

Gemini 2.5 Flash

Ultra-fast model with best cost-performance

Core Features:
- 1M tokens context window
- Fastest response speed in industry
- Ultra-low price
- Multimodal support
- Suitable for high-frequency calls
Pricing:
- Check the console for real-time pricing
Suitable Scenarios:
- Daily conversations
- Quick queries
- Batch processing
- Real-time applications
- Cost-sensitive projects

Gemini 1.0 Series

Gemini 1.0 Pro

Classic model, stable and reliable

Core Features:
- 32K context window
- Stable performance
- Good multilingual support
- Balanced cost and performance
Pricing:
- Check the console for real-time pricing
Suitable Scenarios:
- Standard dialogue
- Text generation
- Translation tasks
- General queries

Gemini Vision (Pro Vision)

Image understanding model

Core Features:
- Strong image understanding
- Supports multi-image analysis
- Precise OCR capabilities
- Scene description
Pricing:
- Input: $0.25/1M tokens
- Image: $0.0025/image
Suitable Scenarios:
- Image content analysis
- Document OCR
- Multi-image comparison
- Visual Q&A

Experimental Models

Gemini 2.0 Flash Exp

Latest experimental model, free to use

Core Features:
- 1M tokens context window
- Latest model architecture
- Completely free (limited time)
- May have instability
Pricing:
- Completely free (experimental phase)
Suitable Scenarios:
- Testing and validation
- Development prototypes
- Feature exploration
- Non-critical applications

Usage Methods

Basic Text Dialogue

from openai import OpenAI

client = OpenAI(
    api_key="YOUR_API_KEY",
    base_url="https://api2.laozhang.ai/v1"
)

# Use Gemini 2.5 Flash
response = client.chat.completions.create(
    model="gemini-2.5-flash",
    messages=[
        {"role": "system", "content": "You are a helpful assistant"},
        {"role": "user", "content": "Explain how the Internet works"}
    ],
    temperature=0.7,
    max_tokens=1000
)

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

import OpenAI from 'openai';

const openai = new OpenAI({
  apiKey: 'YOUR_API_KEY',
  baseURL: 'https://api2.laozhang.ai/v1'
});

// Use Gemini 2.5 Flash
const response = await openai.chat.completions.create({
  model: 'gemini-2.5-flash',
  messages: [
    { role: 'system', content: 'You are a helpful assistant' },
    { role: 'user', content: 'Explain how the Internet works' }
  ],
  temperature: 0.7,
  max_tokens: 1000
});

console.log(response.choices[0].message.content);

curl https://api2.laozhang.ai/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "gemini-2.5-flash",
    "messages": [
      {"role": "system", "content": "You are a helpful assistant"},
      {"role": "user", "content": "Explain how the Internet works"}
    ]
  }'

Application Scenarios

1. Ultra-Long Document Analysis

Leverage Gemini’s 2M tokens context to process entire books:

# Read entire book or long document
with open('long_book.txt', 'r', encoding='utf-8') as f:
    book_content = f.read()

response = client.chat.completions.create(
    model="gemini-2.5-pro",  # 2M context
    messages=[
        {
            "role": "user",
            "content": f"""
            Please analyze this book and provide:
            1. Main theme summary
            2. Character relationship diagram
            3. Plot structure analysis
            4. Insights and evaluation

            Book content:
            {book_content}
            """
        }
    ],
    max_tokens=4000
)

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

2M Tokens = About 1.5 Million Words

A typical novel: 80,000-100,000 words
Gemini 2.5 Pro can process 15-18 novels simultaneously!

2. Code Repository Understanding

Analyze entire code repositories:

import os

def read_code_files(directory):
    """Read all code files"""
    code_content = []
    for root, dirs, files in os.walk(directory):
        for file in files:
            if file.endswith(('.py', '.js', '.java', '.cpp')):
                file_path = os.path.join(root, file)
                with open(file_path, 'r', encoding='utf-8') as f:
                    code_content.append(f"=== {file_path} ===\n{f.read()}\n")
    return '\n'.join(code_content)

# Read entire project
project_code = read_code_files('./my_project')

response = client.chat.completions.create(
    model="gemini-2.5-pro",
    messages=[
        {
            "role": "user",
            "content": f"""
            Please analyze this code repository and provide:
            1. Project architecture overview
            2. Key module functions
            3. Code quality assessment
            4. Improvement suggestions

            Code content:
            {project_code}
            """
        }
    ],
    max_tokens=3000
)

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

3. Multi-Image Analysis

Analyze multiple images simultaneously:

response = client.chat.completions.create(
    model="gemini-2.5-flash",
    messages=[
        {
            "role": "user",
            "content": [
                {"type": "text", "text": "Compare these product images and analyze their design styles and features"},
                {
                    "type": "image_url",
                    "image_url": {"url": "https://example.com/product1.jpg"}
                },
                {
                    "type": "image_url",
                    "image_url": {"url": "https://example.com/product2.jpg"}
                },
                {
                    "type": "image_url",
                    "image_url": {"url": "https://example.com/product3.jpg"}
                }
            ]
        }
    ]
)

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

4. Document OCR and Information Extraction

response = client.chat.completions.create(
    model="gemini-pro-vision",
    messages=[
        {
            "role": "user",
            "content": [
                {
                    "type": "text",
                    "text": """
                    Extract all information from this invoice:
                    1. Invoice number
                    2. Date
                    3. Vendor information
                    4. Item details
                    5. Total amount

                    Output in JSON format
                    """
                },
                {
                    "type": "image_url",
                    "image_url": {"url": "https://example.com/invoice.jpg"}
                }
            ]
        }
    ]
)

import json
invoice_data = json.loads(response.choices[0].message.content)
print(invoice_data)

5. Data Analysis and Visualization

data_prompt = """
Please analyze the following data and provide:
1. Data trends analysis
2. Anomaly detection
3. Correlation analysis
4. Forecasting suggestions

Sales data (last 12 months):
Jan: 12000, Feb: 11500, Mar: 13200, Apr: 14100, May: 13800,
Jun: 15200, Jul: 14900, Aug: 13600, Sep: 14300, Oct: 15800,
Nov: 17200, Dec: 19500
"""

response = client.chat.completions.create(
    model="gemini-2.5-flash",
    messages=[{"role": "user", "content": data_prompt}],
    temperature=0.3  # Lower temperature for more objective analysis
)

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

6. Code Generation

response = client.chat.completions.create(
    model="gemini-2.5-flash",
    messages=[
        {
            "role": "user",
            "content": """
            Write a Python class with these requirements:
            1. Class name: DataProcessor
            2. Functions: read data, process data, save results
            3. Support CSV and JSON formats
            4. Include error handling
            5. Provide usage examples
            """
        }
    ],
    temperature=0.5
)

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

Gemini’s Unique Advantages

1. Ultra-Long Context Window

Industry Leading: Gemini 2.5 Pro supports 2M tokens context, about 10x Claude and GPT-4

Application Scenarios:

Entire book analysis
Large code repository review
Mass document processing
Long conversation history maintenance

2. Powerful Multimodal Capabilities

Supports multiple modalities including text, images, audio, and video:

# Multi-modal analysis (video + text)
response = client.chat.completions.create(
    model="gemini-2.5-pro",
    messages=[
        {
            "role": "user",
            "content": [
                {"type": "text", "text": "Analyze the content and techniques of this video"},
                {"type": "video_url", "video_url": {"url": "https://example.com/video.mp4"}}
            ]
        }
    ]
)

3. Precise Multimodal Understanding

Gemini has excellent understanding capabilities for images, videos, and audio:

Accurate scene description
Multi-object recognition
Temporal sequence understanding
Audio content analysis

Usage Tips

1. Model Selection Guide

Scenario	Recommended Model	Reason
Daily conversations	Gemini 2.5 Flash	Fastest speed, lowest price
Long documents	Gemini 2.5 Pro	2M context
Image understanding	Gemini Pro Vision	Image-specific optimization
Code generation	Gemini 2.5 Flash	Cost-effective, good quality
Complex reasoning	Gemini 2.5 Pro	Powerful reasoning
Testing	Gemini 2.0 Flash Exp	Free

2. Context Window Management

Short Context (< 128K)

Price advantage:

Gemini 2.5 Flash: $0.075/1M tokens
Gemini 2.5 Pro: $1.25/1M tokens

Suitable for:

Daily conversations
Short document processing
Quick queries

Long Context (> 128K)

Pricing changes:

Gemini 2.5 Flash: $0.15/1M tokens (2x)
Gemini 2.5 Pro: $2.5/1M tokens (2x)

Suitable for:

Entire book analysis
Large code repositories
Mass documents

If document length is near 128K threshold, consider splitting into multiple requests to save costs

3. Prompt Optimization

# ✅ Good prompt example
good_prompt = """
Task: Analyze user feedback data

Requirements:
1. Sentiment classification (positive/negative/neutral)
2. Extract key issues
3. Count issue frequency
4. Provide improvement suggestions

Output format:
{
  "sentiment_analysis": {...},
  "key_issues": [...],
  "suggestions": [...]
}

Feedback data:
[User feedback data]
"""

# ❌ Poor prompt example
bad_prompt = "Analyze this feedback data"

4. Parameter Tuning

number

default:"1"

Control creativity:

0: Most deterministic (translation, facts)
0.7: Balanced (general dialogue)
1.0-1.5: More creative (creative writing)

number

default:"0.95"

Nucleus sampling:

0.9: Conservative
0.95: Balanced
1.0: Most diverse

integer

Top-K sampling:

Gemini-specific parameter
Recommended range: 1-40
Lower values = more deterministic

Cost Optimization Strategies

1. Choose Appropriate Models

Cost First

Gemini 2.5 Flash

Input: $0.075/1M tokens
current price shown in console than GPT-4o
Suitable for most scenarios

Performance First

Gemini 2.5 Pro

Input: $1.25/1M tokens (≤128K)
2M tokens context
Suitable for complex tasks

2. Control Context Length

# ❌ Wasteful
def chat_wasteful(user_input, full_history):
    messages = full_history  # May exceed 128K threshold
    messages.append({"role": "user", "content": user_input})
    return client.chat.completions.create(
        model="gemini-2.5-flash",
        messages=messages
    )

# ✅ Economical
def chat_economical(user_input, recent_history):
    # Keep context under 128K for lower pricing
    messages = recent_history[-10:]  # Only recent messages
    messages.append({"role": "user", "content": user_input})
    return client.chat.completions.create(
        model="gemini-2.5-flash",
        messages=messages
    )

3. Batch Processing

import asyncio
from openai import AsyncOpenAI

client = AsyncOpenAI(
    api_key="YOUR_API_KEY",
    base_url="https://api2.laozhang.ai/v1"
)

async def batch_process(tasks):
    """Parallel batch processing"""
    async_tasks = [
        client.chat.completions.create(
            model="gemini-2.5-flash",
            messages=[{"role": "user", "content": task}]
        )
        for task in tasks
    ]

    results = await asyncio.gather(*async_tasks)
    return [r.choices[0].message.content for r in results]

# Usage
tasks = [
    "Translate this to English: 你好世界",
    "Summarize: [Long text]",
    "Analyze sentiment: [Review text]"
]

results = asyncio.run(batch_process(tasks))

Error Handling

Common Error Codes

Error Code	Description	Solution
400	Invalid request parameters	Check parameter format
401	Invalid API Key	Verify API Key
429	Rate limit exceeded	Implement retry mechanism
500	Server error	Retry later

Retry Mechanism Implementation

import time
from openai import APIError, RateLimitError

def chat_with_retry(messages, max_retries=3):
    """Robust retry mechanism"""
    for attempt in range(max_retries):
        try:
            response = client.chat.completions.create(
                model="gemini-2.5-flash",
                messages=messages
            )
            return response

        except RateLimitError as e:
            if attempt < max_retries - 1:
                wait_time = (2 ** attempt) * 2  # Exponential backoff
                print(f"Rate limited, retrying in {wait_time} seconds...")
                time.sleep(wait_time)
            else:
                raise

        except APIError as e:
            if attempt < max_retries - 1:
                print(f"API error, retrying...")
                time.sleep(2)
            else:
                raise

# Usage
response = chat_with_retry([
    {"role": "user", "content": "Hello"}
])

Streaming Response

For long responses, use streaming for better user experience:

# Streaming output
stream = client.chat.completions.create(
    model="gemini-2.5-flash",
    messages=[
        {"role": "user", "content": "Write a detailed article on AI development history"}
    ],
    stream=True
)

print("Generating content: ", end="")
for chunk in stream:
    if chunk.choices[0].delta.content:
        print(chunk.choices[0].delta.content, end="", flush=True)
print("\n\nGeneration complete!")

// Streaming output
const stream = await openai.chat.completions.create({
  model: 'gemini-2.5-flash',
  messages: [
    { role: 'user', content: 'Write a detailed article on AI development history' }
  ],
  stream: true
});

process.stdout.write('Generating content: ');
for await (const chunk of stream) {
  const content = chunk.choices[0]?.delta?.content;
  if (content) {
    process.stdout.write(content);
  }
}
console.log('\n\nGeneration complete!');

Best Practices

1. Long Document Processing

def process_long_document(document_path):
    """Best practices for processing long documents"""

    # Read document
    with open(document_path, 'r', encoding='utf-8') as f:
        content = f.read()

    # Check length
    token_count = len(content) // 4  # Rough estimate

    # Choose appropriate model
    if token_count < 100000:  # < 100K
        model = "gemini-2.5-flash"  # Lower price tier
    else:  # > 100K
        model = "gemini-2.5-pro"  # More powerful

    response = client.chat.completions.create(
        model=model,
        messages=[
            {
                "role": "user",
                "content": f"Analyze this document:\n\n{content}"
            }
        ],
        max_tokens=2000
    )

    return response.choices[0].message.content

2. Multi-turn Conversation Management

class ConversationManager:
    def __init__(self, model="gemini-2.5-flash", max_history=10):
        self.model = model
        self.max_history = max_history
        self.messages = []

    def chat(self, user_input):
        # Add user message
        self.messages.append({
            "role": "user",
            "content": user_input
        })

        # Keep only recent N messages
        messages_to_send = self.messages[-self.max_history:]

        # Get response
        response = client.chat.completions.create(
            model=self.model,
            messages=messages_to_send
        )

        # Add assistant response
        assistant_message = response.choices[0].message.content
        self.messages.append({
            "role": "assistant",
            "content": assistant_message
        })

        return assistant_message

# Usage
conversation = ConversationManager()
print(conversation.chat("What is AI?"))
print(conversation.chat("What are its application scenarios?"))

3. Structured Output

def get_structured_output(prompt):
    """Get structured JSON output"""
    response = client.chat.completions.create(
        model="gemini-2.5-flash",
        messages=[
            {
                "role": "system",
                "content": "Always return results in JSON format"
            },
            {
                "role": "user",
                "content": f"{prompt}\n\nOutput in JSON format"
            }
        ],
        temperature=0.3  # Lower temperature for more structured output
    )

    import json
    return json.loads(response.choices[0].message.content)

# Usage
result = get_structured_output(
    "Extract structured fields: ticket A-1024, priority high, department engineering"
)
print(result)

Compare with Other Models

Dimension	Gemini 2.5 Flash	GPT-4o Mini	Claude Haiku 4.5
Price	$0.075/1M	$0.15/1M	$1/1M
Context	1M tokens	128K tokens	200K tokens
Speed	⭐⭐⭐⭐⭐	⭐⭐⭐⭐⭐	⭐⭐⭐⭐⭐
Cost-performance	⭐⭐⭐⭐⭐	⭐⭐⭐⭐	⭐⭐⭐
Long documents	⭐⭐⭐⭐⭐	⭐⭐⭐	⭐⭐⭐⭐
Code generation	⭐⭐⭐⭐	⭐⭐⭐⭐	⭐⭐⭐⭐⭐

Recommendation:

Ultra-long documents → Gemini 2.5 Pro (2M context)
Cost-sensitive → Gemini 2.5 Flash (lowest price)
Code generation → Claude Haiku 4.5 (strongest capabilities)
Image understanding → GPT-4o (best multimodal)
General applications → Gemini 2.5 Flash (best balance)

Chat Completions API - Complete API documentation
OpenAI Models - GPT series models guide
Claude Models - Anthropic Claude models guide
Pricing - Detailed model pricing information

​Model Overview

​Model Classification

​Gemini 3.1 / 2.5 Series

​Gemini 1.0 Series

​Experimental Models

​Usage Methods

​Basic Text Dialogue

​Application Scenarios

​1. Ultra-Long Document Analysis

​2. Code Repository Understanding

​3. Multi-Image Analysis

​4. Document OCR and Information Extraction

​5. Data Analysis and Visualization

​6. Code Generation

​Gemini’s Unique Advantages

​1. Ultra-Long Context Window

​2. Powerful Multimodal Capabilities

​3. Precise Multimodal Understanding

​Usage Tips

​1. Model Selection Guide

​2. Context Window Management

​3. Prompt Optimization

​4. Parameter Tuning

​Cost Optimization Strategies

​1. Choose Appropriate Models

Cost First

Performance First

​2. Control Context Length

​3. Batch Processing

​Error Handling

​Common Error Codes

​Retry Mechanism Implementation

​Streaming Response

​Best Practices

​1. Long Document Processing

​2. Multi-turn Conversation Management

​3. Structured Output

​Compare with Other Models

​Related Resources

Model Overview

Model Classification

Gemini 3.1 / 2.5 Series

Gemini 1.0 Series

Experimental Models

Usage Methods

Basic Text Dialogue

Application Scenarios

1. Ultra-Long Document Analysis

2. Code Repository Understanding

3. Multi-Image Analysis

4. Document OCR and Information Extraction

5. Data Analysis and Visualization

6. Code Generation

Gemini’s Unique Advantages

1. Ultra-Long Context Window

2. Powerful Multimodal Capabilities

3. Precise Multimodal Understanding

Usage Tips

1. Model Selection Guide

2. Context Window Management

3. Prompt Optimization

4. Parameter Tuning

Cost Optimization Strategies

1. Choose Appropriate Models

2. Control Context Length

3. Batch Processing

Error Handling

Common Error Codes

Retry Mechanism Implementation

Streaming Response

Best Practices

1. Long Document Processing

2. Multi-turn Conversation Management

3. Structured Output

Compare with Other Models

Related Resources