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scroll_up

Scroll up web pages by pixel amounts or full pages to navigate content in Steel MCP Server's browser automation.

Instructions

Scroll up the page by a pixel amount - if no pixels are specified, scrolls up one page

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
pixelsNoThe number of pixels to scroll up. If not specified, scrolls up one page.

Implementation Reference

  • The handler function for the scroll_up tool. It scrolls up the page by the specified pixels or one page using PageUp if not specified.
    async function handleScrollUp(page: Page, args: any): Promise<CallToolResult> {
      const { pixels } = args;
      if (pixels !== undefined) {
        await page.evaluate((scrollAmount) => {
          window.scrollBy(0, -scrollAmount);
        }, pixels);
      } else {
        await page.keyboard.press("PageUp");
      }
    
      return {
        isError: false,
        content: [{ type: "text", text: `Scrolled up by ${pixels ?? "one page"}` }],
      };
    }
  • The input schema and metadata definition for the scroll_up tool, including name, description, and inputSchema.
    {
      name: "scroll_up",
      description:
        "Scroll up the page by a pixel amount - if no pixels are specified, scrolls up one page",
      inputSchema: {
        type: "object",
        properties: {
          pixels: {
            type: "integer",
            description:
              "The number of pixels to scroll up. If not specified, scrolls up one page.",
          },
        },
        required: [],
      },
    },
  • src/index.ts:931-932 (registration)
    The switch case in handleToolCall that registers and dispatches to the scroll_up handler.
    case "scroll_up":
      result = await handleScrollUp(page, args);
Behavior2/5

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

No annotations are provided, so the description carries the full burden. It discloses the default behavior (scrolls up one page if no pixels specified) and the action (scrolling up), but lacks details on behavioral traits such as whether scrolling is smooth or instant, if it respects page boundaries, what happens at the top of the page, or any error conditions. For a tool with zero annotation coverage, this is a significant gap in transparency.

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

Conciseness5/5

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

The description is appropriately sized and front-loaded, consisting of a single, efficient sentence that directly states the tool's purpose and default behavior. Every word earns its place, with no redundancy or unnecessary elaboration.

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

Completeness3/5

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

Given the tool's low complexity (one optional parameter, no output schema, no annotations), the description is minimally adequate. It covers the basic action and default behavior, but as a navigation tool with no annotations, it should ideally provide more context on usage scenarios, limitations, or interactions with sibling tools to be fully complete.

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?

Schema description coverage is 100%, with the parameter 'pixels' fully documented in the schema. The description adds minimal value beyond the schema by restating the default behavior ('if no pixels are specified, scrolls up one page'), which is already covered in the schema description. Since the schema does the heavy lifting, the baseline score 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's purpose: 'Scroll up the page by a pixel amount' specifies the verb (scroll up) and resource (the page). It distinguishes from siblings like 'scroll_down' by direction, but doesn't explicitly differentiate from other navigation tools like 'navigate' or 'go_back' beyond the scrolling action.

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

Usage Guidelines3/5

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

The description implies usage context through the default behavior ('if no pixels are specified, scrolls up one page'), suggesting it's for fine-grained or page-level upward scrolling. However, it doesn't provide explicit guidance on when to use this versus alternatives like 'navigate' for URL-based navigation or 'scroll_down' for downward scrolling, nor does it mention any exclusions.

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

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