capture_screenshot

Capture application window screenshots as PNG images, returning base64 data or saving to file for automated testing and documentation.

Instructions

Capture a screenshot of the application window. Returns base64-encoded PNG image data by default.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`filename`	No	Optional filename (without extension) to save the screenshot. If not provided, a timestamp will be used.
`returnBase64`	No	Whether to return base64 image data (true) or save to file and return path (false). Default: true

Implementation Reference

src/tools/screenshot.ts:11-42 (handler)

Primary handler function for the 'capture_screenshot' tool. Processes input parameters, invokes the TauriDriver's screenshot method, and returns a standardized ToolResponse with base64 data or file path.

export async function captureScreenshot(
  driver: TauriDriver,
  params: ScreenshotParams = {}
): Promise<ToolResponse<{ path?: string; base64?: string; message: string }>> {
  try {
    const returnBase64 = params.returnBase64 ?? true; // Default to base64 for MCP
    const result = await driver.captureScreenshot(params.filename, returnBase64);

    if (returnBase64) {
      return {
        success: true,
        data: {
          base64: result,
          message: 'Screenshot captured successfully',
        },
      };
    } else {
      return {
        success: true,
        data: {
          path: result,
          message: `Screenshot saved to: ${result}`,
        },
      };
    }
  } catch (error) {
    return {
      success: false,
      error: error instanceof Error ? error.message : String(error),
    };
  }
}

src/index.ts:232-260 (handler)

MCP server CallToolRequest handler case for 'capture_screenshot'. Calls the tool function and formats the response, including special handling for image content in MCP format.

case 'capture_screenshot': {
  const result = await captureScreenshot(driver, args as any);

  if (result.success && result.data?.base64) {
    // Return both text description and image
    return {
      content: [
        {
          type: 'text',
          text: result.data.message,
        },
        {
          type: 'image',
          data: result.data.base64,
          mimeType: 'image/png',
        },
      ],
    };
  }

  return {
    content: [
      {
        type: 'text',
        text: JSON.stringify(result, null, 2),
      },
    ],
  };
}

src/index.ts:84-101 (registration)

Registration of the 'capture_screenshot' tool in the MCP server's ListToolsRequest handler, including name, description, and input schema.

{
  name: 'capture_screenshot',
  description: 'Capture a screenshot of the application window. Returns base64-encoded PNG image data by default.',
  inputSchema: {
    type: 'object',
    properties: {
      filename: {
        type: 'string',
        description: 'Optional filename (without extension) to save the screenshot. If not provided, a timestamp will be used.',
      },
      returnBase64: {
        type: 'boolean',
        description: 'Whether to return base64 image data (true) or save to file and return path (false). Default: true',
        default: true,
      },
    },
  },
},

src/tauri-driver.ts:99-115 (helper)

Low-level implementation in TauriDriver class that captures the screenshot using WebDriverIO's takeScreenshot(), returns base64 or saves to file.

async captureScreenshot(filename?: string, returnBase64: boolean = false): Promise<string> {
  this.ensureAppRunning();

  const screenshot = await this.appState.browser!.takeScreenshot();

  if (returnBase64) {
    return screenshot;
  }

  // Save to file
  const timestamp = new Date().toISOString().replace(/[:.]/g, '-');
  const fileName = filename ? `${filename}.png` : `screenshot-${timestamp}.png`;
  const filePath = path.join(this.config.screenshotDir, fileName);

  await fs.writeFile(filePath, screenshot, 'base64');
  return filePath;
}

MCP Tauri Automation