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The FLUX MCP server provides access to all FLUX models through the Model Context Protocol. Generate and edit images using natural language in Claude.

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Available Models

ModelDescription
FLUX.2 [pro]Best balance of speed, quality, and cost — generation & editing with up to 8 reference images - Recommended
FLUX.2 [max]Highest quality generation & editing with grounding search (up to 8 reference images)
FLUX.2 [flex]Optimized for typography — generation & editing with adjustable controls (up to 8 reference images)
FLUX.2 [klein] 9BFast generation & editing with good quality (up to 4 reference images)
FLUX.2 [klein] 4BFastest and most affordable generation & editing (up to 4 reference images)
FLUX1.1 [pro]Fast, high-quality generation
FLUX1.1 [pro] UltraHigh-quality generation up to 4MP resolution
FLUX.1 Kontext [pro]Single-image editing with text instructions
FLUX.1 Kontext [max]Single-image editing with higher quality
FLUX.1 Fill [pro]Intelligent inpainting
FLUX.1 Expand [pro]Smart outpainting

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Setup Instructions

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Claude Desktop

1

Get your BFL API key

Sign up at Black Forest Labs to obtain your API key.
2

Open Claude Desktop configuration

Locate your configuration file:
  • macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
  • Windows: %APPDATA%\Claude\claude_desktop_config.json
3

Add MCP server configuration

Add the following configuration to your claude_desktop_config.json file:
{
  "mcpServers": {
    "bfl-flux": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote",
        "https://flux-mcp-bfl-e21faf2e.koyeb.app/",
        "--header",
        "x-key: ${BFL_API_KEY}"
      ],
      "env": {
        "BFL_API_KEY": "your_bfl_api_key_here"
      }
    }
  }
}
Replace your_bfl_api_key_here with your actual BFL API key obtained in Step 1.
4

Restart Claude Desktop

Quit and restart Claude Desktop to load the new MCP server configuration. The FLUX tools will appear automatically in Claude’s tool list.

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Claude.ai

1

Get your BFL API key

Sign up at Black Forest Labs to obtain your API key.
2

Access Custom Connectors

Navigate to Claude.ai and go to Settings → Custom Connectors.
3

Add a new connector

Configure the connector with the following details:
  • URL: https://flux-mcp-bfl-e21faf2e.koyeb.app/
  • Headers: Add a custom header
    • Name: x-key
    • Value: Your BFL API key
4

Save and start using

Save the connector configuration and start a new conversation. You can now ask Claude to generate images using FLUX models.

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Usage

Once configured, ask Claude to generate or edit images using natural language:
  • “Generate an image of a sunset over mountains”
  • “Create a portrait of a robot in cyberpunk style”
  • “Edit this image to change the sky to a dramatic sunset”
  • “Expand this image to make it wider”
Claude automatically selects the appropriate model and handles the generation process. The MCP server includes automatic polling and returns results when ready.

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Pricing

You are billed directly by Black Forest Labs based on your API usage. Each user uses their own API key for full cost control. Standard BFL API pricing applies - see bfl.ai/pricing.

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Technical Details

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Authentication

Your API key is passed via the x-key header with each request. This provides secure per-user authentication.

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Troubleshooting

  1. Verify your claude_desktop_config.json is formatted correctly (valid JSON)
  2. Ensure you’ve fully restarted Claude Desktop (quit and reopen)
  3. Check that your API key is set correctly in the env section
  4. Look for error messages in Claude Desktop’s developer console
  • Verify your BFL API key is valid and active
  • Ensure the API key is correctly entered without extra spaces or quotes
  • Check that your key has sufficient credits for generation
  • Confirm you’re using the correct header name: x-key
  • The default timeout is 300 seconds (5 minutes)
  • Check the BFL API status at status.bfl.ai
  • Try again with a simpler prompt or lower resolution
  • Verify your network connection is stable
  • Use more detailed and specific prompts
  • Try FLUX.2 [flex]
  • Refer to the Prompting Guide for best practices
  • Experiment with different aspect ratios and parameters

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Best Practices

  • Use specific prompts: Include details about style, lighting, composition, and subject for best results
  • Start with FLUX.2 [pro]: Best balance of quality, speed, and cost for both generation and editing
  • Iterate on results: Refine your prompt if the first generation isn’t perfect
  • Monitor usage: Track API usage through the BFL dashboard