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scroll_page

Scroll a webpage up or down by a percentage of the viewport to load lazy-loaded content and trigger infinite scroll, with feedback on actual movement and page end.

Instructions

Scroll the page up or down by a percentage of the viewport.

The way to trigger lazy-loaded content and infinite scroll; take a fresh take_snapshot afterwards to see what was added.

The response reports how far the page actually moved and whether the end has been reached, so a scroll loop has something to stop on: "did not move" means you are at the end, and a page height that keeps growing means more content is still loading.

To bring one known element into view, scroll_to_selector is more precise. click already scrolls to its target, so no scrolling is needed before it.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
amountNoHow far to scroll, as a percentage of the viewport height — 25 is a quarter screen, 100 a full screen.
browserNoWhich browser to act on. Each name is an independent Chrome, created on first use. Omit for the shared default; parallel agents each need their own name.default
directionNoDirection to scroll.down

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
resultYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed1 schema field changedv2.5.0
    • addedInput schema / properties / browser
      Added value: +{
+  "default": "default",
+  "description": "Which browser to act on. Each name is an independent Chrome, created on first use. Omit for the shared default; parallel agents each need their own name.",
+  "type": "string"
+}
  2. First observedv1.7.2

TDQS

A4.7/5.0
Behavior5/5

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

Annotations already declare readOnlyHint=false and destructiveHint=false, and the description adds useful behavioral detail beyond that: scrolling can trigger lazy loading, the response reports actual movement and end-of-page status, and did not move signals the boundary while growing page height means loading is ongoing. This gives an agent concrete loop-termination criteria.

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 dense but every sentence earns its place: core behavior first, then the typical use case, then response semantics for loops, then when not to use it. It is front-loaded and avoids repetition of schema content.

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?

With no required parameters, a fully described schema, and an output schema available, the description covers the remaining gaps: when the tool is appropriate, what side effect it triggers, how to interpret the response, and which sibling to prefer instead. The agent has enough context to call it correctly and structure a scroll loop.

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%, so the schema already explains amount, browser, and direction. The description reinforces the viewport-percentage semantics but does not add meaningful parameter information beyond what the input schema provides, so it stays at the baseline for high schema coverage.

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 opens with a specific verb and resource: 'Scroll the page up or down by a percentage of the viewport.' It also distinguishes itself from siblings by noting that scroll_to_selector is more precise for bringing a known element into view, so an agent can tell scroll_page apart from nearby tools.

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 states exactly when to use it: to trigger lazy-loaded content and infinite scroll. It also gives a clear exclusion by saying click already scrolls to its target so no scrolling is needed first, and names scroll_to_selector as the alternative for targeting a known element.

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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