scroll

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

The only annotation is readOnlyHint=false, which conveys no mechanism. The phrase 'real mouse wheel' is genuinely additive: it tells the agent this dispatches trusted wheel input (triggering real wheel listeners, lazy-loading, smooth-scroll behavior) rather than a programmatic scrollTop change. The deltaY sign convention is also disclosed. It stops short of noting that the viewport/state is mutated or how deltas are interpreted.

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?

One sentence, front-loaded with the action, with the directional convention parenthesized as a secondary detail. No filler.

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?

With 10 parameters, no output schema, and near-zero annotation coverage, the description leaves real gaps: delta units/magnitude are unstated, and 'over an element' implies a target even though every element-addressing parameter is optional (only deltaY is required), so the no-target behavior is undefined. Adequate but with clear holes.

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 80%, so the baseline is 3, but deltaX/deltaY are the two undocumented parameters and the description supplies the missing meaning for the required one ('deltaY > 0 scrolls down'), including that it is a real wheel delta rather than a CSS offset. The remaining element-targeting parameters are adequately covered by the schema.

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 pairs the specific verb 'scrolls' with the mechanism ('real mouse wheel') and target ('over an element'), which separates it cleanly from click/hover/type/key siblings. It does not name a sibling explicitly, but the action is unambiguous.

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?

Usage is only implied: the agent can infer you call this to scroll a page or container, and 'over an element' hints at element targeting. There is no statement about when to prefer this over eval/script, and no note about what happens when no element is supplied.

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