Image Generator MCP Server

Instructions

Implementation Reference

• src/image-generator.ts:12-20 (handler)

  Core handler function that generates the image using OpenAI DALL-E 3 API and returns base64 encoded image.

  async generateImage(prompt: string, size: ImageGenerateParams['size'] = "1024x1024") {
      const response = await this.openai.images.generate({
          model: IMAGE_MODEL,
          prompt,
          size,
          response_format: 'b64_json'
      });
      return response.data[0].b64_json;
  }

• src/index.ts:77-102 (handler)

  MCP CallToolRequestSchema handler specifically for 'generate_image': validates args, calls ImageGenerator, saves image file, returns resource URI.

  if (request.params.name !== "generate_image") {
    throw new McpError(
      ErrorCode.MethodNotFound,
      `Unknown tool: ${request.params.name}`
    );
  }
  
  if (!isValidImageGenerationArgs(request.params.arguments)) {
    throw new McpError(
      ErrorCode.InvalidParams,
      "Invalid image generation arguments"
    )
  };
  
  const { prompt, imageName } = request.params.arguments;
  const base64 = await new ImageGenerator().generateImage(prompt);
  const fileName = `${imageName.replace(/\..*$/, '')}.png`;
  const filepath = await imageSaver.saveBase64(fileName, base64!);
  
  return {
    toolResult: {
      uri: `file://${filepath}`,
      type: 'image',
      mimeType: 'image/png'
    }
  }

• src/index.ts:53-71 (registration)

  Tool registration in ListToolsRequestSchema handler, including name, description, and input schema.

    tools: [{
      name: "generate_image",
      description: "Generate an image from a prompt.",
      inputSchema: {
        type: "object",
        properties: {
          prompt: {
            type: "string",
            description: "A prompt detailing what image to generate."
          },
          imageName: {
            type: "string",
            description: "The filename for the image excluding any extensions."
          }
        },
        required: ["prompt", "imageName"]
      }
    }]
  })

• src/types.ts:6-13 (schema)

  Validation function for generate_image input arguments matching the schema.

  export function isValidImageGenerationArgs(args: any): args is ImageGenerationRequestParams {
      return typeof args === "object" &&
          args !== null &&
          "prompt" in args &&
          typeof args.prompt === 'string' &&
          "imageName" in args &&
          typeof args.imageName === 'string';  
  }

• src/types.ts:1-4 (schema)

  TypeScript interface defining the input parameters for generate_image tool.

  export interface ImageGenerationRequestParams {
      prompt: string;
      imageName: string;
  }