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

Annotations already declare the safety profile (not read-only, non-destructive, openWorld, non-idempotent), so the bar is lower. The description adds genuine behavioral context beyond that: hovering is the mechanism for surfacing hover menus/tooltips as a precursor to a click. It doesn't mention whether hovering triggers JS state changes or any wait/timeout behavior.

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 with zero filler: the action and scope come first, then the purpose clause, then the disambiguation clause. Every clause 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?

For a simple two-parameter interaction tool with no output schema and annotations covering safety, the description supplies everything needed: action, target, intent, and the sibling it is not for. Nothing required for correct invocation is missing.

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 both params are already documented (pageId 'from web_navigate', selector as a CSS selector). The description only restates 'by pageId' and adds no syntax or format detail. Baseline 3 is appropriate when the schema does the heavy lifting.

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 (hover) plus the resource and scope (an element in the DESKTOP grid browser, addressed by pageId). It explicitly contrasts itself with the sibling webpage_hover for phones/tablets, so an agent can pick the right tool without opening either 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?

Gives an explicit when-to-use ('to open a hover menu or reveal a tooltip before clicking') and names the alternative (webpage_hover) with the condition that selects it ('for a phone or tablet'). Nothing 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.