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

With no output schema, the sentence "Answers the page after it: the elements and text in view, with the same numbers" is genuinely valuable – it tells the agent that a scroll returns a fresh page snapshot with stable element numbering, so no follow-up read is needed. It also discloses that lazily loaded content will materialize. Minor tension: repeated `down`/`screens` calls move further, which sits awkwardly with idempotentHint=true, though this is an annotation nuance rather than a description contradiction.

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 dense sentences with the scroll modes front-loaded and the return behavior last, which matches reading order for a caller. The closing clause "with the same numbers" is terse to the point of being cryptic without context from sibling tools, costing a point.

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 five-parameter, zero-required tool with no output schema, this covers the mode space and the return payload adequately. Remaining gaps are minor: no statement about waiting for content to settle after scrolling, no indication of what happens at the end of a page, and no guidance on how `inside` and `element` interact when used together.

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 100%, so the baseline would be 3, but the description goes slightly further by expressing mode-parameter relationships in prose – `screens` is scoped to down/up, `element` switches to scroll-until-visible, and `inside` scopes the scroll to a panel or list. That helps an agent reason about which parameters combine, even though most individual meanings are already in 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 gives a concrete verb ("Scrolls with the mouse wheel") and then enumerates every mode: up/down by `screens`, to top/bottom, until an `element` is in view, or inside a panel/list. That enumeration makes it unmistakably the scrolling tool among siblings like cotlet_browser_find, cotlet_browser_read, and cotlet_browser_click, without needing to open the schema.

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?

"Content that loads on scroll appears" hints at the main use case (lazy/infinite-loaded content) and "until `element` is in view" implies a bring-off-screen-element-into-view scenario. However, it never explicitly says when to prefer this over cotlet_browser_find or cotlet_browser_read, and gives no exclusions or prerequisites, so routing is left to inference.

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