QR Code MCP Server

Instructions

Implementation Reference

• src/index.ts:39-77 (handler)

  The core handler function that implements the tool logic: destructures input, builds QR options, generates data URL with qrcode library, returns image content or error response.

  async ({ text, options = {} }) => {
    try {
      const qrOptions = {
        errorCorrectionLevel: options.errorCorrectionLevel || 'M',
        width: options.width,
        margin: options.margin || defaultMargin,
        color: {
          dark: options.color?.dark || getDefaultDarkColor(),
          light: options.color?.light || getDefaultLightColor()
        }
      };
  
      const dataUrl = await QRCode.toDataURL(text, qrOptions);
      
      return {
        content: [
          {
            type: "text",
            text: `QR code generated successfully for: "${text}"`
          },
          {
            type: "image",
            data: dataUrl,
            mimeType: options.type || "image/png"
          }
        ]
      };
    } catch (error) {
      return {
        content: [
          {
            type: "text",
            text: `Error generating QR code: ${error instanceof Error ? error.message : 'Unknown error'}`
          }
        ],
        isError: true
      };
    }
  }

• src/index.ts:17-26 (schema)

  Zod schema defining customizable options for QR code generation (error level, size, margin, colors, output type), used in the tool's inputSchema.

  const QRCodeOptionsSchema = z.object({
    errorCorrectionLevel: z.enum(['L', 'M', 'Q', 'H']).optional().default('M'),
    width: z.number().min(50).max(2000).optional(),
    margin: z.number().min(0).max(10).optional().default(defaultMargin),
    color: z.object({
      dark: z.string().optional().default(getDefaultDarkColor()),
      light: z.string().optional().default(getDefaultLightColor())
    }).optional(),
    type: z.enum(['image/png', 'image/jpeg', 'image/webp']).optional().default('image/png')
  });

• src/index.ts:29-78 (registration)

  MCP tool registration via server.registerTool, specifying name, metadata (title/description), input schema, and handler function.

  server.registerTool(
    "generate-qrcode-dataurl",
    {
      title: "Generate QR Code as Data URL",
      description: "Generate a QR code from text or URL and return it as a base64 data URL",
      inputSchema: {
        text: z.string().min(1).describe("The text or URL to encode in the QR code"),
        options: QRCodeOptionsSchema.optional().describe("QR code generation options")
      }
    },
    async ({ text, options = {} }) => {
      try {
        const qrOptions = {
          errorCorrectionLevel: options.errorCorrectionLevel || 'M',
          width: options.width,
          margin: options.margin || defaultMargin,
          color: {
            dark: options.color?.dark || getDefaultDarkColor(),
            light: options.color?.light || getDefaultLightColor()
          }
        };
  
        const dataUrl = await QRCode.toDataURL(text, qrOptions);
        
        return {
          content: [
            {
              type: "text",
              text: `QR code generated successfully for: "${text}"`
            },
            {
              type: "image",
              data: dataUrl,
              mimeType: options.type || "image/png"
            }
          ]
        };
      } catch (error) {
        return {
          content: [
            {
              type: "text",
              text: `Error generating QR code: ${error instanceof Error ? error.message : 'Unknown error'}`
            }
          ],
          isError: true
        };
      }
    }
  );

• src/index.ts:293-299 (helper)

  Utility functions providing default hex color values for QR code foreground (dark) and background (light), used in options merging.

  function getDefaultLightColor(): string {
    return '#FFFFFF';
  }
  
  function getDefaultDarkColor(): string {
    return '#000000';
  }

• src/index.ts:14-14 (helper)

  Default margin value for QR code generation, used as fallback in options.

  const defaultMargin = 4;