ui_scroll

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

With no annotations, the description carries the behavioral burden. It discloses a key non-obvious behavior: scrolling is what creates off-viewport DOM rows in virtualised containers, which directly affects when the agent must call it. It could mention side effects or return behavior, but the core behavioral caveat is covered.

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, no filler, with the primary operation front-loaded and the critical virtualised-list context stated immediately. Every sentence earns its place.

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 the rich schema coverage and the lack of an output schema, the description plus schema is sufficient for an agent to invoke scrolling correctly. The virtualisation warning is important context that the schema cannot express. It could slightly expand on failure behavior, but the core invocation context is complete enough.

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?

The input schema covers 100% of the 8 parameters with meaningful descriptions, so the baseline is 3. The description does not add extra parameter nuance beyond the schema, but it does not need to because the schema is already thorough.

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 the page or a specific container. It also gives a concrete motivating use case—virtualised lists/grids—which makes its purpose unmistakable and distinct from all sibling UI tools.

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 clearly says when to use the tool: before interacting with anything in a virtualised list or grid, where off-screen rows are not in the DOM. It does not explicitly name alternatives or when-not cases, but the scroll function is unique among the listed siblings and the guidance is otherwise strong.

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