firefox-devtools-mcp

Instructions

Implementation Reference

• src/tools/utilities.ts:95-116 (handler)

  MCP tool handler function that acquires Firefox instance and calls dismissDialog(), with specific error handling for no active dialog.

  export async function handleDismissDialog(_args: unknown): Promise<McpToolResponse> {
    try {
      const { getFirefox } = await import('../index.js');
      const firefox = await getFirefox();
  
      try {
        await firefox.dismissDialog();
        return successResponse('✅ Dismissed');
      } catch (error) {
        const errorMsg = (error as Error).message;
  
        // Concise error for no active dialog
        if (errorMsg.includes('no such alert') || errorMsg.includes('No dialog')) {
          throw new Error('No active dialog');
        }
  
        throw error;
      }
    } catch (error) {
      return errorResponse(error as Error);
    }
  }

• src/tools/utilities.ts:23-30 (schema)

  Tool schema definition with name 'dismiss_dialog', description, and empty input schema (no parameters required).

  export const dismissDialogTool = {
    name: 'dismiss_dialog',
    description: 'Dismiss browser dialog.',
    inputSchema: {
      type: 'object',
      properties: {},
    },
  };

• src/index.ts:142-146 (registration)

  Registration of the dismiss_dialog handler in the central toolHandlers Map used by the MCP Server for tool execution.

  // Utilities
  ['accept_dialog', tools.handleAcceptDialog],
  ['dismiss_dialog', tools.handleDismissDialog],
  ['navigate_history', tools.handleNavigateHistory],
  ['set_viewport_size', tools.handleSetViewportSize],

• src/index.ts:186-190 (registration)

  Inclusion of dismissDialogTool in the allTools array, which is returned in response to listTools requests.

  // Utilities
  tools.acceptDialogTool,
  tools.dismissDialogTool,
  tools.navigateHistoryTool,
  tools.setViewportSizeTool,

• src/firefox/pages.ts:65-74 (helper)

  Core Firefox PageManagement helper method that uses WebDriver to switch to the alert dialog and dismiss it.

  async dismissDialog(): Promise<void> {
    try {
      const alert = await this.driver.switchTo().alert();
      await alert.dismiss();
    } catch (error) {
      throw new Error(
        `Failed to dismiss dialog: ${error instanceof Error ? error.message : String(error)}`
      );
    }
  }