next_page

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 when index is omitted ('scroll the whole document') but says nothing about what happens at the end of the document, whether the scroll is animated or waits for lazy-loaded content, or whether any permission/auth is required. That is adequate for a low-risk scroll action but leaves real behavioral gaps.

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

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

Two sentences, front-loaded with the core action and the caveat folded in efficiently; nothing is redundant within the body. The bracketed preamble is boilerplate-ish framing rather than tool-specific information, which costs it the top score.

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

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

For a two-parameter, no-output-schema, no-annotation tool, the description covers the action, the browser context, and the index default. Nothing critical is missing for correct invocation, though the page-end/termination behavior would be useful given there is no output schema to clarify results.

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

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

Schema description coverage is 100%, so the baseline is 3, but the description goes beyond the schema by explaining the semantics of omitting index ('If no index is specified, scroll the whole document'), which the schema's 'index of the element' does not convey. It adds no guidance on the intent parameter, so it is not a 5.

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

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

States a specific verb and resource ('Scroll the document in the window or an element to the next page'), which is distinct from the sibling scrolling tools scroll_to_top, scroll_to_bottom, scroll_to_percent and previous_page. The bracketed preamble further differentiates it from non-browser siblings by declaring it drives a real Chrome browser. It does not, however, explicitly name the sibling it is not (e.g. a one-page-at-a-time vs. arbitrary-offset distinction).

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

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

The preamble gives a clear when-to-use condition: 'use only when the task requires acting on a real website.' That is a genuine scoping rule rather than implied guidance. It stops short of routing within the scroll family (no mention of when previous_page or scroll_to_bottom would be preferable), so it is not a 5.

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