mcp-flux-schnell

Instructions

Implementation Reference

• src/index.ts:79-186 (handler)

  Handler for the 'generate_image' tool: validates inputs, checks env vars, calls Flux Schnell API via fetch, saves base64 image to file, returns file path.

  case "generate_image": {
    // Validate environment variables
    if (!FLUX_API_URL) {
      return {
        content: [
          {
            type: "text",
            text: "Configuration Error: FLUX_API_URL environment variable is not set",
          },
        ],
      };
    }
    if (!FLUX_API_TOKEN) {
      return {
        content: [
          {
            type: "text",
            text: "Configuration Error: FLUX_API_TOKEN environment variable is not set",
          },
        ],
      };
    }
  
    // Validate input parameters
    const validationResult = generateImageSchema.safeParse(
      request.params.arguments
    );
    if (!validationResult.success) {
      return {
        content: [
          {
            type: "text",
            text: `Input Error: ${validationResult.error.message}`,
          },
        ],
      };
    }
  
    const { prompt } = validationResult.data;
    const timestamp = new Date().getTime();
    const filename = `flux-${timestamp}.png`;
    const directory = WORKING_DIR;
    const filepath = join(directory, filename);
  
    // Check if directory exists and create it if it doesn't
    if (!existsSync(directory)) {
      try {
        await mkdir(directory, { recursive: true });
      } catch (error) {
        return {
          content: [
            {
              type: "text",
              text: `Directory Error: Failed to create directory ${directory}: ${error instanceof Error ? error.message : 'Unknown error'}`,
            },
          ],
        };
      }
    }
  
    try {
      // Call Flux Schnell API
      const response = await fetch(FLUX_API_URL, {
        method: "POST",
        headers: {
          Authorization: `Bearer ${FLUX_API_TOKEN}`,
          "Content-Type": "application/json",
        },
        body: JSON.stringify({ prompt }),
      });
  
      if (!response.ok) {
        const errorText = await response.text();
        return {
          content: [
            {
              type: "text",
              text: `API Error: Flux API returned status ${response.status}: ${errorText}`,
            },
          ],
        };
      }
  
      const result = await response.json();
      const base64Data = result.image.replace(/^data:image\/png;base64,/, "");
      await writeFile(filepath, Buffer.from(base64Data, "base64"));
  
      return {
        content: [
          {
            type: "text",
            text: `Image saved successfully:\nFilename: ${filename}\nPath: ${filepath}`,
          },
        ],
      };
    } catch (error: unknown) {
      const errorMessage =
        error instanceof Error ? error.message : "An unknown error occurred";
      return {
        content: [
          {
            type: "text",
            text: `Operation Error: Failed to generate or save image: ${errorMessage}`,
          },
        ],
      };
    }
  }

• src/index.ts:25-27 (schema)

  Zod schema for validating 'generate_image' tool input: requires a prompt string between 1-2048 chars.

  const generateImageSchema = z.object({
    prompt: z.string().min(1).max(2048),
  });

• src/index.ts:49-70 (registration)

  Registration of 'generate_image' tool in ListToolsRequestSchema handler, including name, description, and inputSchema.

  return {
    tools: [
      {
        name: "generate_image",
        description:
          "Generate an image from a text prompt using Flux Schnell model",
        inputSchema: {
          type: "object",
          properties: {
            prompt: {
              type: "string",
              minLength: 1,
              maxLength: 2048,
              description:
                "A text description of the image you want to generate.",
            },
          },
          required: ["prompt"],
        },
      },
    ],
  };