FLUX MCP Server

Instructions

Implementation Reference

• index.js:297-315 (handler)

  Handler for the 'flux_models' tool within the CallToolRequestSchema request handler. It maps over FLUX_MODELS and returns a JSON string of model metadata including display name, kind, image acceptance, notes, and key inputs.

  if (name === "flux_models") {
    const models = Object.entries(FLUX_MODELS).map(([model, meta]) => ({
      model,
      display: meta.display,
      kind: meta.kind,
      accepts_image: meta.accepts_image,
      notes: meta.notes,
      key_inputs: Object.keys(meta.inputs),
    }));
  
    return {
      content: [
        {
          type: "text",
          text: JSON.stringify(models, null, 2),
        },
      ],
    };
  }

• index.js:206-213 (registration)

  Registration of the 'flux_models' tool in the ListToolsRequestSchema response, defining its name, description, and empty input schema.

  {
    name: "flux_models",
    description: "List supported FLUX models with usage notes and key inputs",
    inputSchema: {
      type: "object",
      properties: {},
    },
  },

• index.js:17-103 (helper)

  Helper constant FLUX_MODELS defining metadata for all supported FLUX models, including display names, kinds, notes, input schemas, and image acceptance flags. Used by the flux_models handler to generate the tool response.

  const FLUX_MODELS = {
    "black-forest-labs/flux-1.1-pro-ultra": {
      display: "FLUX1.1 Pro Ultra",
      kind: "text-to-image",
      notes: [
        "Highest quality, up to ~4MP; 'raw' mode for realism.",
        "Use when you need best composition/large output.",
      ],
      inputs: {
        prompt: { required: true, type: "string" },
        raw: { required: false, type: "boolean" },
        aspect_ratio: { required: false, type: "string" },
        seed: { required: false, type: "integer" },
        output_quality: { required: false, type: "number" },
        go_fast: { required: false, type: "boolean" },
      },
      accepts_image: false,
    },
    "black-forest-labs/flux-pro": {
      display: "FLUX1.1 Pro",
      kind: "text-to-image",
      notes: [
        "Fast, reliable, commercial-grade default when Ultra not required.",
      ],
      inputs: {
        prompt: { required: true, type: "string" },
        aspect_ratio: { required: false, type: "string" },
        seed: { required: false, type: "integer" },
      },
      accepts_image: false,
    },
    "black-forest-labs/flux-redux-dev": {
      display: "FLUX.1 Redux [dev]",
      kind: "image-variation",
      notes: [
        "Variations/restyling while preserving key elements; mix image + text.",
      ],
      inputs: {
        image: { required: true, type: "file_or_url" },
        prompt: { required: true, type: "string" },
        strength: { required: false, type: "number" },
        seed: { required: false, type: "integer" },
        num_outputs: { required: false, type: "integer" },
      },
      accepts_image: true,
    },
    "black-forest-labs/flux-fill-pro": {
      display: "FLUX.1 Fill [pro]",
      kind: "inpainting/outpainting",
      notes: ["Professional in/outpainting; provide mask for areas to change."],
      inputs: {
        image: { required: true, type: "file_or_url" },
        mask: { required: false, type: "file_or_url" },
        prompt: { required: true, type: "string" },
        num_inference_steps: { required: false, type: "integer" },
        guidance: { required: false, type: "number" },
        seed: { required: false, type: "integer" },
      },
      accepts_image: true,
    },
    "black-forest-labs/flux-depth-dev": {
      display: "FLUX.1 Depth [dev]",
      kind: "depth-guided editing",
      notes: [
        "Structure-preserving edits/style transfer using depth; supply an image.",
      ],
      inputs: {
        image: { required: true, type: "file_or_url" },
        prompt: { required: true, type: "string" },
        seed: { required: false, type: "integer" },
      },
      accepts_image: true,
    },
    "black-forest-labs/flux-canny-pro": {
      display: "FLUX.1 Canny [pro]",
      kind: "edge-guided generation",
      notes: [
        "Control structure/composition with edges; ideal for sketches/wireframes → detailed images.",
      ],
      inputs: {
        image: { required: true, type: "file_or_url" },
        prompt: { required: true, type: "string" },
        seed: { required: false, type: "integer" },
      },
      accepts_image: true,
    },
  };