Mistral AI

The Mistral AI API provides access to cutting-edge language models that deliver exceptional performance at competitive pricing. Mistral offers a compelling alternative to OpenAI and other providers, with specialized models for reasoning, code generation, and multimodal tasks.

Mistral is particularly valuable for:

Cost-effective AI integration with pricing up to 8x lower than competitors
Advanced reasoning with Magistral models that show step-by-step thinking
Code generation excellence with Codestral models supporting 80+ programming languages
Multimodal capabilities for text and image processing
Enterprise deployments with on-premises options requiring just 4 GPUs
Multilingual applications with native support for 12+ languages

Why Choose Mistral?

Mistral Medium 3 offers GPT-4 class performance at $0.40/$2.00 per million tokens (input/output), representing significant cost savings compared to OpenAI's $2.50/$10.00 pricing for similar capabilities.

API Key

To use Mistral AI, you need to set the MISTRAL_API_KEY environment variable, or specify the apiKey in the provider configuration.

Example of setting the environment variable:

export MISTRAL_API_KEY=your_api_key_here

Configuration Options

The Mistral provider supports extensive configuration options:

Basic Options

providers:
  - id: mistral:mistral-large-latest
    config:
      # Model behavior
      temperature: 0.7 # Creativity (0.0-2.0)
      top_p: 0.95 # Nucleus sampling (0.0-1.0)
      max_tokens: 4000 # Response length limit

      # Advanced options
      safe_prompt: true # Content filtering
      random_seed: 42 # Deterministic outputs
      frequency_penalty: 0.1 # Reduce repetition
      presence_penalty: 0.1 # Encourage diversity

JSON Mode

Force structured JSON output:

providers:
  - id: mistral:mistral-large-latest
    config:
      response_format:
        type: 'json_object'
      temperature: 0.3 # Lower temp for consistent JSON

tests:
  - vars:
      prompt: "Extract name, age, and occupation from: 'John Smith, 35, engineer'. Return as JSON."
    assert:
      - type: is-json
      - type: javascript
        value: JSON.parse(output).name === "John Smith"

Authentication Configuration

providers:
  # Option 1: Environment variable (recommended)
  - id: mistral:mistral-large-latest

  # Option 2: Direct API key (not recommended for production)
  - id: mistral:mistral-large-latest
    config:
      apiKey: 'your-api-key-here'

  # Option 3: Custom environment variable
  - id: mistral:mistral-large-latest
    config:
      apiKeyEnvar: 'CUSTOM_MISTRAL_KEY'

  # Option 4: Custom endpoint
  - id: mistral:mistral-large-latest
    config:
      apiHost: 'custom-proxy.example.com'
      apiBaseUrl: 'https://custom-api.example.com/v1'

Advanced Model Configuration

providers:
  # Reasoning model with optimal settings
  - id: mistral:magistral-medium-latest
    config:
      temperature: 0.7
      top_p: 0.95
      max_tokens: 40960 # Full context for reasoning

  # Code generation with FIM support
  - id: mistral:codestral-latest
    config:
      temperature: 0.2 # Low for consistent code
      max_tokens: 8000
      stop: ['```'] # Stop at code block end

  # Multimodal configuration
  - id: mistral:pixtral-12b
    config:
      temperature: 0.5
      max_tokens: 2000
      # Image processing options handled automatically

Environment Variables Reference

Variable	Description	Example
`MISTRAL_API_KEY`	Your Mistral API key (required)	`sk-1234...`
`MISTRAL_API_HOST`	Custom hostname for proxy setup	`api.example.com`
`MISTRAL_API_BASE_URL`	Full base URL override	`https://api.example.com/v1`

Model Selection

You can specify which Mistral model to use in your configuration. The following models are available:

Chat Models

Premier Models

Model	Context	Input Price	Output Price	Best For
`mistral-large-latest`	128k	$2.00/1M	$6.00/1M	Complex reasoning, enterprise tasks
`mistral-medium-latest`	128k	$0.40/1M	$2.00/1M	Balanced performance and cost
`codestral-latest`	256k	$0.30/1M	$0.90/1M	Code generation, 80+ languages
`magistral-medium-latest`	40k	$2.00/1M	$5.00/1M	Advanced reasoning, step-by-step thinking

Free Models

Model	Context	Input Price	Output Price	Best For
`mistral-small-latest`	128k	$0.10/1M	$0.30/1M	General tasks, cost-effective
`magistral-small-latest`	40k	$0.50/1M	$1.50/1M	Reasoning on a budget
`open-mistral-nemo`	128k	$0.15/1M	$0.15/1M	Multilingual, research
`pixtral-12b`	128k	$0.15/1M	$0.15/1M	Vision + text, multimodal

Legacy Models (Deprecated)

open-mistral-7b, mistral-tiny, mistral-tiny-2312
open-mistral-nemo, open-mistral-nemo-2407, mistral-tiny-2407, mistral-tiny-latest
mistral-small-2402
mistral-medium-2312, mistral-medium
mistral-large-2402
mistral-large-2407
codestral-2405
codestral-mamba-2407, open-codestral-mamba, codestral-mamba-latest
open-mixtral-8x7b, mistral-small, mistral-small-2312
open-mixtral-8x22b, open-mixtral-8x22b-2404

Embedding Model

mistral-embed - $0.10/1M tokens - 8k context

Here's an example config that compares different Mistral models:

providers:
  - mistral:mistral-medium-latest
  - mistral:mistral-small-latest
  - mistral:open-mistral-nemo
  - mistral:magistral-medium-latest
  - mistral:magistral-small-latest

Reasoning Models

Mistral's Magistral models are specialized reasoning models announced in June 2025. These models excel at multi-step logic, transparent reasoning, and complex problem-solving across multiple languages.

Key Features of Magistral Models

Chain-of-thought reasoning: Models provide step-by-step reasoning traces before arriving at final answers
Multilingual reasoning: Native reasoning capabilities across English, French, Spanish, German, Italian, Arabic, Russian, Chinese, and more
Transparency: Traceable thought processes that can be followed and verified
Domain expertise: Optimized for structured calculations, programmatic logic, decision trees, and rule-based systems

Magistral Model Variants

Magistral Small (magistral-small-2506): 24B parameter open-source version under Apache 2.0 license
Magistral Medium (magistral-medium-2506): More powerful enterprise version with enhanced reasoning capabilities

Usage Recommendations

For reasoning tasks, consider using these parameters for optimal performance:

providers:
  - id: mistral:magistral-medium-latest
    config:
      temperature: 0.7
      top_p: 0.95
      max_tokens: 40960 # Recommended for reasoning tasks

Multimodal Capabilities

Mistral offers vision-capable models that can process both text and images:

Image Understanding

Use pixtral-12b for multimodal tasks:

providers:
  - id: mistral:pixtral-12b
    config:
      temperature: 0.7
      max_tokens: 1000

tests:
  - vars:
      prompt: 'What do you see in this image?'
      image: 'data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQABAAD...'

Supported Image Formats

JPEG, PNG, GIF, WebP
Maximum size: 20MB per image
Resolution: Up to 2048x2048 pixels optimal

Function Calling & Tool Use

Mistral models support advanced function calling for building AI agents and tools:

providers:
  - id: mistral:mistral-large-latest
    config:
      temperature: 0.1
      tools:
        - type: function
          function:
            name: get_weather
            description: Get current weather for a location
            parameters:
              type: object
              properties:
                location:
                  type: string
                  description: City name
                unit:
                  type: string
                  enum: ['celsius', 'fahrenheit']
              required: ['location']

tests:
  - vars:
      prompt: "What's the weather like in Paris?"
    assert:
      - type: contains
        value: 'get_weather'

Tool Calling Best Practices

Use low temperature (0.1-0.3) for consistent tool calls
Provide detailed function descriptions
Include parameter validation in your tools
Handle tool call errors gracefully

Code Generation

Mistral's Codestral models excel at code generation across 80+ programming languages:

Fill-in-the-Middle (FIM)

providers:
  - id: mistral:codestral-latest
    config:
      temperature: 0.2
      max_tokens: 2000

tests:
  - vars:
      prompt: |
        <fim_prefix>def calculate_fibonacci(n):
            if n <= 1:
                return n
        <fim_suffix>

        # Test the function
        print(calculate_fibonacci(10))
        <fim_middle>
    assert:
      - type: contains
        value: 'fibonacci'

Code Generation Examples

tests:
  - description: 'Python API endpoint'
    vars:
      prompt: 'Create a FastAPI endpoint that accepts a POST request with user data and saves it to a database'
    assert:
      - type: contains
        value: '@app.post'
      - type: contains
        value: 'async def'

  - description: 'React component'
    vars:
      prompt: 'Create a React component for a user profile card with name, email, and avatar'
    assert:
      - type: contains
        value: 'export'
      - type: contains
        value: 'useState'

Complete Working Examples

Example 1: Multi-Model Comparison

description: 'Compare reasoning capabilities across Mistral models'

providers:
  - mistral:magistral-medium-latest
  - mistral:magistral-small-latest
  - mistral:mistral-large-latest
  - mistral:mistral-small-latest

prompts:
  - 'Solve this step by step: {{problem}}'

tests:
  - vars:
      problem: "A company has 100 employees. 60% work remotely, 25% work hybrid, and the rest work in office. If remote workers get a $200 stipend and hybrid workers get $100, what's the total monthly stipend cost?"
    assert:
      - type: llm-rubric
        value: 'Shows clear mathematical reasoning and arrives at correct answer ($13,500)'
      - type: cost
        threshold: 0.10

Example 2: Code Review Assistant

description: 'AI-powered code review using Codestral'

providers:
  - id: mistral:codestral-latest
    config:
      temperature: 0.3
      max_tokens: 1500

prompts:
  - |
    Review this code for bugs, security issues, and improvements:

    ```{{language}}
    {{code}}
    ```

    Provide specific feedback on:
    1. Potential bugs
    2. Security vulnerabilities  
    3. Performance improvements
    4. Code style and best practices

tests:
  - vars:
      language: 'python'
      code: |
        import subprocess

        def run_command(user_input):
            result = subprocess.run(user_input, shell=True, capture_output=True)
            return result.stdout.decode()
    assert:
      - type: contains
        value: 'security'
      - type: llm-rubric
        value: 'Identifies shell injection vulnerability and suggests safer alternatives'

Example 3: Multimodal Document Analysis

description: 'Analyze documents with text and images'

providers:
  - id: mistral:pixtral-12b
    config:
      temperature: 0.5
      max_tokens: 2000

tests:
  - vars:
      prompt: |
        Analyze this document image and:
        1. Extract key information
        2. Summarize main points
        3. Identify any data or charts
      image_url: 'https://example.com/financial-report.png'
    assert:
      - type: llm-rubric
        value: 'Accurately extracts text and data from the document image'
      - type: length
        min: 200

Authentication & Setup

Environment Variables

# Required
export MISTRAL_API_KEY="your-api-key-here"

# Optional - for custom endpoints
export MISTRAL_API_BASE_URL="https://api.mistral.ai/v1"
export MISTRAL_API_HOST="api.mistral.ai"

Getting Your API Key

Visit console.mistral.ai
Sign up or log in to your account
Navigate to API Keys section
Click Create new key
Copy and securely store your key

Security Best Practices

Never commit API keys to version control
Use environment variables or secure vaults
Rotate keys regularly
Monitor usage for unexpected spikes

Performance Optimization

Model Selection Guide

Use Case	Recommended Model	Why
Cost-sensitive apps	`mistral-small-latest`	Best price/performance ratio
Complex reasoning	`magistral-medium-latest`	Step-by-step thinking
Code generation	`codestral-latest`	Specialized for programming
Vision tasks	`pixtral-12b`	Multimodal capabilities
High-volume production	`mistral-medium-latest`	Balanced cost and quality

Context Window Optimization

providers:
  - id: mistral:magistral-medium-latest
    config:
      max_tokens: 8000 # Leave room for 32k input context
      temperature: 0.7

Cost Management

# Monitor costs across models
defaultTest:
  assert:
    - type: cost
      threshold: 0.05 # Alert if cost > $0.05 per test

providers:
  - id: mistral:mistral-small-latest # Most cost-effective
    config:
      max_tokens: 500 # Limit output length

Troubleshooting

Common Issues

Authentication Errors

Error: 401 Unauthorized

Solution: Verify your API key is correctly set:

echo $MISTRAL_API_KEY
# Should output your key, not empty

Rate Limiting

Error: 429 Too Many Requests

Solutions:

Implement exponential backoff
Use smaller batch sizes
Consider upgrading your plan

# Reduce concurrent requests
providers:
  - id: mistral:mistral-large-latest
    config:
      timeout: 30000 # Increase timeout

Context Length Exceeded

Error: Context length exceeded

Solutions:

Truncate input text
Use models with larger context windows
Implement text summarization for long inputs

providers:
  - id: mistral:mistral-medium-latest # 128k context
    config:
      max_tokens: 4000 # Leave room for input

Model Availability

Error: Model not found

Solution: Check model names and use latest versions:

providers:
  - mistral:mistral-large-latest # ✅ Use latest
  # - mistral:mistral-large-2402  # ❌ Deprecated

Debugging Tips

Enable debug logging:
```
export DEBUG=promptfoo:*
```

Test with simple prompts first:

tests:
  - vars:
      prompt: 'Hello, world!'

Check token usage:

tests:
  - assert:
      - type: cost
        threshold: 0.01

Getting Help

Documentation: docs.mistral.ai
Community: Discord
Support: [email protected]
Status: status.mistral.ai

Working Examples

Ready-to-use examples are available in our GitHub repository:

📋 Complete Mistral Example Collection

Run any of these examples locally:

npx promptfoo@latest init --example mistral

Individual Examples:

AIME2024 Mathematical Reasoning - Evaluate Magistral models on advanced mathematical competition problems
Model Comparison - Compare reasoning across Magistral and traditional models
Function Calling - Demonstrate tool use and function calling
JSON Mode - Structured output generation
Code Generation - Multi-language code generation with Codestral
Reasoning Tasks - Advanced step-by-step problem solving
Multimodal - Vision capabilities with Pixtral

Quick Start

# Try the basic comparison
npx promptfoo@latest eval -c https://raw.githubusercontent.com/promptfoo/promptfoo/main/examples/mistral/promptfooconfig.comparison.yaml

# Test mathematical reasoning with Magistral models
npx promptfoo@latest eval -c https://raw.githubusercontent.com/promptfoo/promptfoo/main/examples/mistral/promptfooconfig.aime2024.yaml

# Test reasoning capabilities
npx promptfoo@latest eval -c https://raw.githubusercontent.com/promptfoo/promptfoo/main/examples/mistral/promptfooconfig.reasoning.yaml

Contribute Examples

Found a great use case? Contribute your example to help the community!

API Key​

Configuration Options​

Basic Options​

JSON Mode​

Authentication Configuration​

Advanced Model Configuration​

Environment Variables Reference​

Model Selection​

Chat Models​

Premier Models​

Free Models​

Legacy Models (Deprecated)​

Embedding Model​

Reasoning Models​

Key Features of Magistral Models​

Magistral Model Variants​

Usage Recommendations​

Multimodal Capabilities​

Image Understanding​

Supported Image Formats​

Function Calling & Tool Use​

Tool Calling Best Practices​

Code Generation​

Fill-in-the-Middle (FIM)​

Code Generation Examples​

Complete Working Examples​

Example 1: Multi-Model Comparison​

Example 2: Code Review Assistant​

Example 3: Multimodal Document Analysis​

Authentication & Setup​

Environment Variables​

Getting Your API Key​

Performance Optimization​

Model Selection Guide​

Context Window Optimization​

Cost Management​

Troubleshooting​

Common Issues​

Authentication Errors​

Rate Limiting​

Context Length Exceeded​

Model Availability​

Debugging Tips​

Getting Help​

Working Examples​

📋 Complete Mistral Example Collection​

Quick Start​