MCP Accessibility Scanner

Instructions

Implementation Reference

• src/tools/snapshot.ts:128-147 (handler)

  Executes the browser_click tool: resolves element locator from params, generates code snippet for click/dblclick, performs the action via Playwright on the tab's page.

  handle: async (tab, params, response) => {
    response.setIncludeSnapshot();
  
    const locator = await tab.refLocator(params);
    const button = params.button;
    const buttonAttr = button ? `{ button: '${button}' }` : '';
  
    if (params.doubleClick)
      response.addCode(`await page.${await generateLocator(locator)}.dblclick(${buttonAttr});`);
    else
      response.addCode(`await page.${await generateLocator(locator)}.click(${buttonAttr});`);
  
  
    await tab.waitForCompletion(async () => {
      if (params.doubleClick)
        await locator.dblclick({ button });
      else
        await locator.click({ button });
    });
  },

• src/tools/snapshot.ts:108-126 (schema)

  Defines Zod schemas for input validation: base elementSchema (element desc, ref), clickSchema extending it with doubleClick and button options. Used in tool schema with name 'browser_click'.

  export const elementSchema = z.object({
    element: z.string().describe('Human-readable element description used to obtain permission to interact with the element'),
    ref: z.string().describe('Exact target element reference from the page snapshot'),
  });
  
  const clickSchema = elementSchema.extend({
    doubleClick: z.boolean().optional().describe('Whether to perform a double click instead of a single click'),
    button: z.enum(['left', 'right', 'middle']).optional().describe('Button to click, defaults to left'),
  });
  
  const click = defineTabTool({
    capability: 'core',
    schema: {
      name: 'browser_click',
      title: 'Click',
      description: 'Perform click on a web page',
      inputSchema: clickSchema,
      type: 'destructive',
    },

• src/tools.ts:38-56 (registration)

  Registers the browser_click tool by including the snapshot module's tools (via ...snapshot) in the allTools array, which is filtered into _tools used by BrowserServerBackend for MCP listTools().

  export const allTools: Tool<any>[] = [
    ...common,
    ...console,
    ...dialogs,
    ...evaluate,
    ...files,
    ...form,
    ...install,
    ...keyboard,
    ...navigate,
    ...network,
    ...mouse,
    ...pdf,
    ...screenshot,
    ...snapshot,
    ...tabs,
    ...wait,
    ...verify,
  ];

• src/browserServerBackend.ts:38-42 (registration)

  In BrowserServerBackend constructor, sets this._tools = filteredTools(config), which includes browser_click, used for dispatching calls and listing in MCP.

  constructor(config: FullConfig, factory: BrowserContextFactory) {
    this._config = config;
    this._browserContextFactory = factory;
    this._tools = filteredTools(config);
  }

• src/browserServerBackend.ts:61-63 (registration)

  BrowserServerBackend.listTools() converts tool schemas including browser_click to MCP Tool format for registration with the MCP server.

  async listTools(): Promise<mcpServer.Tool[]> {
    return this._tools.map(tool => toMcpTool(tool.schema));
  }