scroll

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

With no annotations, the description carries the behavioral burden and does well: it discloses the approximate scroll distance, default behavior without an element, targeted behavior with an element, return value ('Scrolled'), and a follow-up action. It does not mention edge cases such as reaching the end of a list or failure behavior, which keeps it from a 5.

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?

The description is front-loaded with the core action and amount, then covers directions, element behavior, return value, and the swipe alternative in a compact paragraph. Every clause contributes useful guidance without repetition.

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?

Given no annotations and no output schema, the description supplies the necessary behavioral context: how far it scrolls, how element targeting works, what it returns, and the recommended follow-up. It lacks only minor edge-case behavior, such as what happens at the end of a scrollable area.

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 coverage is only 50%, but the description fully compensates: it explains each direction's meaning ('down' shows further down, 'up' goes back, 'left'/'right' for carousels and tabs) and clarifies that element is an optional scrollable element id from read_screen, including what happens when it is omitted.

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?

The description states a specific verb and resource ('Scroll a list or page'), specifies the scroll amount ('about a third of its height or width'), and explains the intended outcome ('reach content that isn't on screen yet'). It also distinguishes the four directions and hints at scope via the element parameter.

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?

It explicitly covers when to use the tool for page/list scrolling versus 'swipe' for precise dragging, and says to call read_screen afterward to see results. It also clarifies the behavior with and without an element id, leaving little ambiguity about invocation context.

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