Skip to main content
Glama
Wladastic

AutoProbeMCP

by Wladastic

check_scrollability

Determine if a web page supports scrolling in vertical, horizontal, or both directions, enabling automated verification of scrollability.

Instructions

Check if the page is scrollable in the specified direction

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
directionNoDirection to check for scrollabilityboth

Implementation Reference

  • Zod schema for check_scrollability input validation (direction parameter: 'vertical', 'horizontal', or 'both')
    const CheckScrollabilitySchema = z.object({
      direction: z.enum(['vertical', 'horizontal', 'both']).default('both')
    });
  • src/index.ts:387-401 (registration)
    Tool registration entry for 'check_scrollability' with name, description, and inputSchema (JSON schema)
    {
      name: 'check_scrollability',
      description: 'Check if the page is scrollable in the specified direction',
      inputSchema: {
        type: 'object',
        properties: {
          direction: {
            type: 'string',
            enum: ['vertical', 'horizontal', 'both'],
            default: 'both',
            description: 'Direction to check for scrollability'
          }
        }
      }
    }
  • Handler for 'check_scrollability' tool - evaluates page scroll dimensions in page context, returns scrollability info for vertical/horizontal/both directions
              case 'check_scrollability': {
                if (!currentPage) {
                  throw new Error('No browser page available. Launch a browser first.');
                }
    
                const params = CheckScrollabilitySchema.parse(args);
                const { direction } = params;
    
                // Check scrollability with proper typing
                const scrollInfo = await currentPage.evaluate((dir) => {
                  const documentHeight = Math.max(
                    document.body.scrollHeight,
                    document.body.offsetHeight,
                    document.documentElement.clientHeight,
                    document.documentElement.scrollHeight,
                    document.documentElement.offsetHeight
                  );
                  
                  const documentWidth = Math.max(
                    document.body.scrollWidth,
                    document.body.offsetWidth,
                    document.documentElement.clientWidth,
                    document.documentElement.scrollWidth,
                    document.documentElement.offsetWidth
                  );
                  
                  const viewportHeight = window.innerHeight;
                  const viewportWidth = window.innerWidth;
                  
                  const verticalScrollable = documentHeight > viewportHeight;
                  const horizontalScrollable = documentWidth > viewportWidth;
                  
                  const currentScrollY = window.scrollY;
                  const currentScrollX = window.scrollX;
                  const maxScrollY = Math.max(0, documentHeight - viewportHeight);
                  const maxScrollX = Math.max(0, documentWidth - viewportWidth);
                  
                  const verticalInfo = {
                    scrollable: verticalScrollable,
                    currentPosition: currentScrollY,
                    maxScroll: maxScrollY,
                    canScrollDown: currentScrollY < maxScrollY,
                    canScrollUp: currentScrollY > 0
                  };
                  
                  const horizontalInfo = {
                    scrollable: horizontalScrollable,
                    currentPosition: currentScrollX,
                    maxScroll: maxScrollX,
                    canScrollRight: currentScrollX < maxScrollX,
                    canScrollLeft: currentScrollX > 0
                  };
                  
                  return {
                    direction: dir,
                    vertical: verticalInfo,
                    horizontal: horizontalInfo,
                    anyScrollable: verticalScrollable || horizontalScrollable
                  };
                }, direction);
    
                // Format the response message based on direction
                let message = '';
                
                if (direction === 'both') {
                  const v = scrollInfo.vertical;
                  const h = scrollInfo.horizontal;
                  message = `Page scrollability status:
    Vertical: ${v.scrollable ? 'Scrollable' : 'Not scrollable'}${v.scrollable ? ` (${v.currentPosition}/${v.maxScroll})` : ''}
    Horizontal: ${h.scrollable ? 'Scrollable' : 'Not scrollable'}${h.scrollable ? ` (${h.currentPosition}/${h.maxScroll})` : ''}
    Overall: ${scrollInfo.anyScrollable ? 'Page is scrollable' : 'Page is not scrollable'}`;
                } else if (direction === 'vertical') {
                  const v = scrollInfo.vertical;
                  message = `Vertical scrolling: ${v.scrollable ? 'Available' : 'Not available'}`;
                  if (v.scrollable) {
                    message += `\nPosition: ${v.currentPosition}/${v.maxScroll}`;
                    message += `\nCan scroll up: ${v.canScrollUp}`;
                    message += `\nCan scroll down: ${v.canScrollDown}`;
                  }
                } else {
                  const h = scrollInfo.horizontal;
                  message = `Horizontal scrolling: ${h.scrollable ? 'Available' : 'Not available'}`;
                  if (h.scrollable) {
                    message += `\nPosition: ${h.currentPosition}/${h.maxScroll}`;
                    message += `\nCan scroll left: ${h.canScrollLeft}`;
                    message += `\nCan scroll right: ${h.canScrollRight}`;
                  }
                }
    
                return {
                  content: [
                    {
                      type: 'text',
                      text: message
                    }
                  ]
                };
              }
Behavior2/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description should disclose behavior such as return value (e.g., boolean) or side effects. It only restates the tool's basic function, leaving the agent in the dark about expected output.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single concise sentence with the verb 'Check' front-loaded. While very brief, it earnestly communicates the core function without wasted words.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool has no output schema and only one parameter, the description should at least hint at the return type (e.g., boolean). It fails to provide complete context for an AI agent to use effectively.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema already provides a description for the 'direction' parameter (100% coverage). The tool description adds no additional meaning, so a baseline of 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool checks scrollability in a specified direction, distinguishing it from sibling 'scroll' which performs scrolling. However, it could be more specific about returning a boolean.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

No guidance is given on when to use this tool versus alternatives like 'scroll' or other page state checks. The AI agent has no context for when to invoke it.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Install Server

Other Tools

Latest Blog Posts

MCP directory API

We provide all the information about MCP servers via our MCP API.

curl -X GET 'https://glama.ai/api/mcp/v1/servers/Wladastic/AutoProbeMCP'

If you have feedback or need assistance with the MCP directory API, please join our Discord server