Replicate FLUX.1 Kontext [Max] MCP Server

A Model Context Protocol (MCP) server that provides access to FLUX.1 Kontext [Max] - the frontier image generation model through the Replicate API. This server enables high-quality image generation with advanced text rendering capabilities and superior contextual understanding.

🔗 Repository: https://github.com/PierrunoYT/replicate-flux-kontext-max-mcp-server

🚀 Ready to use! Pre-built executable included - no compilation required.

✅ Enhanced Reliability: Server handles missing API tokens gracefully without crashes and includes robust error handling.

Features

• Frontier Image Generation: Uses FLUX.1 Kontext [Max] - the latest frontier model via Replicate API
• Advanced Text Rendering: Superior text integration and rendering capabilities
• Contextual Understanding: Enhanced understanding of complex prompts and context
• Image Editing Support: Both text-to-image and image editing capabilities
• Automatic Image Download: Generated images are automatically saved to local images directory
• Multiple Aspect Ratios: Support for 1:1, 16:9, 9:16, 4:3, 3:4, 3:2, 2:3, 4:5, 5:4, 21:9, 9:21, 2:1, 1:2
• Reproducible Results: Optional seed parameter for consistent outputs
• Prediction Management: Track, monitor, and cancel running predictions
• Flexible Output Formats: Support for JPEG and PNG formats
• Safety Controls: Configurable safety tolerance levels (0-6)
• Detailed Responses: Returns both local file paths and original URLs with metadata
• Robust Error Handling: Graceful handling of missing API tokens without server crashes
• Universal Portability: Works anywhere with npx - no local installation required
• Enhanced Reliability: Graceful shutdown handlers and comprehensive error reporting

Prerequisites

• Node.js 18 or higher
• Replicate API token

Installation

1. Get your Replicate API Token

• Visit Replicate
• Sign up for an account
• Navigate to your account settings
• Generate an API token (starts with r8_)

2. Clone or Download

git clone https://github.com/PierrunoYT/replicate-flux-kontext-max-mcp-server.git
cd replicate-flux-kontext-max-mcp-server

3. Install Dependencies (Optional)

The server is pre-built, but if you want to modify it:

npm install
npm run build

Configuration

🚀 Recommended: Universal npx Configuration (Works Everywhere)

Best option for portability - works on any machine with Node.js:

{
  "mcpServers": {
    "replicate-flux-kontext-max": {
      "command": "npx",
      "args": [
        "-y",
        "https://github.com/PierrunoYT/replicate-flux-kontext-max-mcp-server.git"
      ],
      "env": {
        "REPLICATE_API_TOKEN": "r8_your-replicate-api-token-here"
      }
    }
  }
}

Benefits:

• ✅ Universal Access: Works on any machine with Node.js
• ✅ No Local Installation: npx downloads and runs automatically
• ✅ Always Latest Version: Pulls from GitHub repository
• ✅ Cross-Platform: Windows, macOS, Linux compatible
• ✅ Settings Sync: Works everywhere you use your MCP client

Alternative: Local Installation

If you prefer to install locally, use the path helper:

npm run get-path

This will output the complete MCP configuration with the correct absolute path.

For Claude Desktop

Add to ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

{
  "mcpServers": {
    "replicate-flux-kontext-max": {
      "command": "node",
      "args": ["path/to/replicate-flux-kontext-max-mcp-server/build/index.js"],
      "env": {
        "REPLICATE_API_TOKEN": "r8_your-replicate-api-token-here"
      }
    }
  }
}

For Kilo Code MCP Settings

Add to your MCP settings file at: C:\Users\[username]\AppData\Roaming\Kilo-Code\MCP\settings\mcp_settings.json

{
  "mcpServers": {
    "replicate-flux-kontext-max": {
      "command": "node",
      "args": ["path/to/replicate-flux-kontext-max-mcp-server/build/index.js"],
      "env": {
        "REPLICATE_API_TOKEN": "r8_your-replicate-api-token-here"
      },
      "disabled": false,
      "alwaysAllow": []
    }
  }
}

Available Tools

flux_kontext_max_generate

Generate images using FLUX.1 Kontext [Max] with real-time processing via Replicate.

Parameters:

• prompt (required): Text description of the image to generate, or instruction on how to edit the given image
• input_image (optional): Image to use as reference. Must be jpeg, png, gif, or webp. Can be a URL or base64 data URI
• seed (optional): Random seed for reproducible generation
• aspect_ratio (optional): "match_input_image", "1:1", "16:9", "9:16", "4:3", "3:4", "3:2", "2:3", "4:5", "5:4", "21:9", "9:21", "2:1", "1:2" (default: "match_input_image")
• output_format (optional): "jpg" or "png" (default: "jpg")
• safety_tolerance (optional): Safety level 0-6 (default: 2)

Response includes:

• Image URLs for immediate access
• Generation metadata (seed, prediction details)
• File information (content type, dimensions)
• Local file paths for downloaded images

flux_kontext_max_generate_async

Generate images using FLUX.1 Kontext [Max] with async prediction tracking for monitoring progress.

Parameters: Same as flux_kontext_max_generate

Use this tool when:

• You want to monitor generation progress
• Working with complex prompts that might take longer
• Need detailed prediction tracking and logging

Features:

• Prediction-based processing with status polling
• 5-minute timeout with progress updates
• Detailed logging of generation progress
• Prediction ID returned for tracking

flux_kontext_max_cancel_prediction

Cancel a running prediction by its ID.

Parameters:

• prediction_id (required): The ID of the prediction to cancel

Use this tool when:

• You need to stop a long-running generation
• Want to free up resources
• Made a mistake in the prompt and want to start over

flux_kontext_max_get_prediction

Get the status and details of a prediction by its ID.

Parameters:

• prediction_id (required): The ID of the prediction to check

Response includes:

• Current prediction status
• Creation and completion timestamps
• Input parameters used
• Output results (if completed)
• Error details (if failed)
• Generation logs

📥 How Image Download Works

The Replicate FLUX.1 Kontext [Max] MCP server automatically downloads generated images to your local machine. Here's the complete process:

1. Image Generation Flow

1. API Call: Server calls Replicate's FLUX.1 Kontext [Max] API
2. Response: Replicate returns URLs for generated images
3. Auto-Download: Server immediately downloads images to local storage
4. Response: Returns both local paths and original URLs

2. Download Implementation

Download Function (downloadImage):

async function downloadImage(url: string, filename: string): Promise<string> {
  // 1. Parse the URL and determine HTTP/HTTPS client
  const parsedUrl = new URL(url);
  const client = parsedUrl.protocol === 'https:' ? https : http;
  
  // 2. Create 'images' directory if it doesn't exist
  const imagesDir = path.join(process.cwd(), 'images');
  if (!fs.existsSync(imagesDir)) {
    fs.mkdirSync(imagesDir, { recursive: true });
  }
  
  // 3. Create file write stream
  const filePath = path.join(imagesDir, filename);
  const file = fs.createWriteStream(filePath);
  
  // 4. Download and pipe to file
  client.get(url, (response) => {
    response.pipe(file);
    // Handle completion and errors
  });
}

Filename Generation (generateImageFilename):

function generateImageFilename(prompt: string, index: number, seed?: number): string {
  // Creates safe filename: flux_kontext_max_prompt_seed_index_timestamp.jpg
  const safePrompt = prompt
    .toLowerCase()
    .replace(/[^a-z0-9\s]/g, '')  // Remove special characters
    .replace(/\s+/g, '_')         // Replace spaces with underscores
    .substring(0, 50);            // Limit length
  
  const timestamp = new Date().toISOString().replace(/[:.]/g, '-');
  const seedStr = seed ? `_${seed}` : '';
  return `flux_kontext_max_${safePrompt}${seedStr}_${index}_${timestamp}.jpg`;
}

3. File Storage Details

Directory Structure:

your-project/
├── images/                    # Auto-created directory
│   ├── flux_kontext_max_mountain_landscape_123456_1_2025-06-24T18-30-45-123Z.jpg
│   ├── flux_kontext_max_cute_robot_789012_1_2025-06-24T18-31-20-456Z.jpg
│   └── ...

Filename Format:

• Prefix: flux_kontext_max_
• Prompt: First 50 chars, sanitized (alphanumeric + underscores)
• Seed: Random seed used for generation (if provided)
• Index: Image number (for multiple images)
• Timestamp: ISO timestamp for uniqueness
• Extension: .jpg or .png based on output_format

4. Response Format

The server returns both local and remote information:

Successfully generated 1 image(s) using FLUX.1 Kontext [Max] via Replicate:

Prompt: "a serene mountain landscape with text 'FLUX' painted in white"
Aspect Ratio: 1:1
Output Format: jpg
Safety Tolerance: 2
Seed: 1234567890

Generated Images:
Image 1:
  Local Path: /path/to/project/images/flux_kontext_max_a_serene_mountain_landscape_1234567890_1_2025-06-24T18-30-45-123Z.jpg
  Original URL: https://replicate.delivery/pbxt/...
  Filename: flux_kontext_max_a_serene_mountain_landscape_1234567890_1_2025-06-24T18-30-45-123Z.jpg

Images have been downloaded to the local 'images' directory.

Example Usage

Basic Image Generation

Generate a photorealistic image of a golden retriever playing in a field of sunflowers with the text "HAPPY DOG" written in bold letters

With Specific Parameters

Generate an image with:
- Prompt: "A minimalist logo design for a tech startup, clean lines, with 'STARTUP' text"
- Aspect ratio: 16:9
- Output format: png
- Seed: 12345

Advanced Usage with Text Rendering

Generate an image of "A futuristic cityscape at night with neon lights and flying cars, large billboard displaying 'FUTURE CITY 2025'" 
with aspect ratio 21:9 and seed 12345 for reproducible results

Text-Heavy Prompts (Kontext [Max] Specialty)

Create an image of a vintage bookstore with multiple book spines showing titles like "The Art of Code", "Digital Dreams", and "Future Stories" clearly readable

Image Editing Examples

Basic Image Editing

Edit this image to add a rainbow in the sky
Input image: https://example.com/landscape.jpg

Complex Image Editing

Edit the image with:
- Prompt: "Add a donut next to the flour on the counter"
- Input image: https://replicate.delivery/pbxt/example.png
- Output format: png

Text Addition to Images

Add the text "SALE 50% OFF" in bold red letters to this storefront image
Input image: https://example.com/storefront.jpg

Prediction Management

Track Generation Progress

Use flux_kontext_max_generate_async to start generation, then use flux_kontext_max_get_prediction with the returned prediction ID to monitor progress

Cancel Long-Running Generation

Use flux_kontext_max_cancel_prediction with the prediction ID if you need to stop generation

Technical Details

Architecture

• Language: TypeScript with ES2022 target
• Runtime: Node.js 18+ with ES modules
• Protocol: Model Context Protocol (MCP) SDK v1.0.0
• API Client: Replicate JavaScript client v0.34.1
• Validation: Zod schema validation

API Model Used

• Model: black-forest-labs/flux-kontext-max on Replicate
• Method: Both direct run() and prediction-based predictions.create()

Error Handling

• Graceful API token handling: Server continues running even without REPLICATE_API_TOKEN set
• No crash failures: Removed process.exit() calls that caused connection drops
• Null safety checks: All tools validate API client availability before execution
• Graceful shutdown: Proper SIGINT and SIGTERM signal handling
• API error catching: Comprehensive error reporting with detailed context
• Timeout handling: Robust async request management with progress updates
• User-friendly messages: Clear error descriptions instead of technical crashes

Development

Project Structure

├── src/
│   └── index.ts          # Main MCP server implementation
├── build/                # Compiled JavaScript (ready to use)
├── test-server.js        # Server testing utility
├── get-path.js          # Configuration path helper
├── example-mcp-config.json # Example configuration
├── package.json         # Project metadata and dependencies
└── tsconfig.json        # TypeScript configuration

Scripts

• npm run build - Compile TypeScript to JavaScript
• npm run dev - Watch mode for development
• npm run start - Start the server directly
• npm run test - Test server startup and basic functionality
• npm run get-path - Get configuration path for your system

Making Changes

1. Edit files in the src/ directory
2. Run npm run build to compile
3. Restart your MCP client to use the updated server

Testing

npm run test

This runs a basic connectivity test that verifies:

• Server starts correctly
• MCP protocol initialization
• Tool discovery functionality

API Costs

This server uses the Replicate platform, which charges per image generation. Check Replicate pricing for current rates.

Typical costs (as of 2024):

• FLUX.1 Kontext [Max]: ~$0.05-0.15 per image
• Costs vary by resolution and complexity

Troubleshooting

Server not appearing in MCP client

1. Recommended: Use the npx configuration for universal compatibility
2. If using local installation, verify the path to build/index.js is correct and absolute
3. Ensure Node.js 18+ is installed: node --version
4. Test server startup: npm run test
5. Restart your MCP client (Claude Desktop, Kilo Code, etc.)
6. Note: Server will start successfully even without REPLICATE_API_TOKEN - check tool responses for API token errors

Image generation failing

1. Verify your Replicate API token is valid and has sufficient credits
2. Check that your prompt follows Replicate's content policy
3. Try simplifying the prompt or adjusting parameters
4. Use the async tool for complex requests
5. Check the server logs for detailed error messages
6. Ensure the FLUX.1 Kontext [Max] model is available in your region

Build issues

If you need to rebuild the server:

npm install
npm run build

Configuration issues

Use the helper script to get the correct path:

npm run get-path

Support

For issues with:

• This MCP server: Create an issue in this repository
• Replicate API: Check Replicate documentation
• MCP Protocol: See MCP documentation

License

MIT License - see LICENSE file for details.

Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Test with npm run test
5. Submit a pull request

Changelog

v1.2.0 (Latest)

• 🔄 API Migration: Migrated from FAL AI to Replicate API
• 🆕 New Tools: Added flux_kontext_max_cancel_prediction and flux_kontext_max_get_prediction
• 📊 Prediction Management: Full prediction lifecycle management with tracking
• 🔧 Enhanced Async: Improved async generation with detailed progress monitoring
• 🛡️ Better Error Handling: Enhanced error reporting and graceful degradation
• 📝 Updated Documentation: Comprehensive documentation for Replicate integration
• ⚡ Performance: Optimized image download and processing pipeline

v1.1.0 (Previous)

• ✨ NEW: Image Editing: Added FLUX.1 Kontext [Max] image editing capabilities
• 🔧 New Tools: flux_kontext_max_edit and flux_kontext_max_edit_async for image editing
• 🖼️ Image Input Support: Accept image URLs and base64 data URIs for editing
• 🎨 Advanced Editing: Complex image modifications with contextual understanding
• 📝 Text Addition: Add text overlays and modifications to existing images
• 🔄 Dual Editing Methods: Both real-time and async queue-based image editing
• 📥 Auto-download: Edited images automatically saved with descriptive filenames

v1.0.0 (Initial)

• 🎨 Image Generation: Basic FLUX.1 Kontext [Max] text-to-image generation
• 📥 Auto-download: Automatic local image saving
• 🔧 MCP Integration: Full Model Context Protocol support
• ⚙️ Configuration: Easy setup with environment variables