Scroll

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

Annotations already declare readOnlyHint=false, openWorldHint=true, idempotentHint=false and destructiveHint=false, so the safety profile is covered. The description adds the genuinely useful behavioral detail that scrolling is smooth and that amount defaults to most of a screen, but says nothing about the viewport change affecting later screenshot/snapshot output or about any side effects.

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?

A single front-loaded sentence that covers the verb, both modes, and the default magnitude with no filler. The phrasing 'by amount pixels' is slightly awkward but costs nothing in length.

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 3-param, no-output-schema tool the description covers both modes and the amount default adequately for correct invocation. It omits where refs originate (presumably the sibling snapshot tool), a minor but real gap for an agent that has not yet captured one.

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 ref, amount and direction are already documented, including the default and the enum. The description restates the same facts ('by amount pixels or most of a screen') without adding format, range, or interaction detail beyond the schema, which is the baseline-3 case.

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 (scroll) plus resource (page/element) and decomposes the tool into its two operating modes: bring a ref into view, or scroll the page in a direction. The scope is unambiguous, though it never names or distinguishes itself from siblings like navigate or snapshot.

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?

"Either bring an element (ref) into view, or scroll the page in a direction" explicitly frames the two mutually exclusive usage modes and which parameter selects which. It gives no exclusions, prerequisites, or named alternative tools, so it stops short of a 5.

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