seleniumbase-mcp

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scroll_page

Scroll the current page vertically.

Instructions

Scroll the current page vertically.

Args: direction: - "up": Scroll upward by amount percent of the window height. - "down": Scroll downward by amount percent of the window height. - "top": Scroll directly to the top; amount is ignored. - "bottom": Scroll directly to the bottom; amount is ignored.

amount: Percentage of the current viewport height used for relative
    up/down scrolling. For example, amount=25 scrolls approximately
    one quarter of the viewport height.

Notes: Values greater than 100 for amount are allowed. For example, 200 means approximately two viewport heights.

Tool selection: - Need to reveal a specific element -> use 'focus_element' with action="scroll_to_element". - Need to scroll the page by a relative amount -> use 'scroll_page'.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`amount`	No
`direction`	No		down

Output Schema

TableJSON Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Addedv1.3.3Sep 13, 2026

TDQS

A4.8/5.0

Behavior4/5

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

Since annotations are absent, the description carries the full burden of behavioral disclosure. It explains how the scroll works (percentage of viewport height, directions, top/bottom ignoring amount, allowed values >100). It does not describe edge cases like page load state or iframes, but for a scrolling tool this is adequate. It adds value beyond the raw schema by explaining semantics.

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 well-organized into sections (Args, Notes, Tool selection). Although it is moderately long, every section earns its place: args explain parameters, notes clarify behavior, and tool selection provides routing guidance. It is front-loaded with the core purpose and avoids redundancy.

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

Completeness5/5

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

Given that an output schema exists, the description need not explain return values (and indeed does not). It covers the parameters thoroughly, provides usage guidelines, and discloses behavioral nuances. All information an agent needs to invoke the tool correctly and decide when to use it is present.

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

Parameters5/5

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

Schema description coverage is 0%, so the description must fully explain parameters. It does so excellently: the 'direction' enum is explained with each value and its effect, and 'amount' is defined as a percentage of viewport height with a concrete example (25 = quarter). It also notes that amount is ignored for 'top' and 'bottom', and that values >100 are allowed. This completeness compensates fully for the absent schema descriptions.

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

Purpose5/5

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 the current page vertically.' It specifies the verb (scroll), the resource (current page), and the direction of action (vertically). It also distinguishes itself from the sibling 'focus_element' by explicitly naming that alternative in the Tool selection section.

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

Usage Guidelines5/5

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

The description provides explicit when-to-use and when-not-to-use guidance: 'Need to reveal a specific element -> use focus_element with action="scroll_to_element". Need to scroll the page by a relative amount -> use scroll_page.' This names the alternative and defines the selection criteria, leaving no ambiguity for the agent.

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