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

Annotations already declare the full behavioral profile (destructiveHint=true, idempotentHint=false, openWorldHint=true), so the bar is lower. The description adds only that the result is revealing children, and does not explain why a merely expanding action is flagged destructive or what happens if the node is already expanded.

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 tight sentences; the action and its target are front-loaded and the prerequisite follows immediately. Nothing is wasted.

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 a full schema, output schema, and rich annotations, the description covers what is needed to call it correctly. Minor gaps remain around pre-expanded state behavior and locator precedence, but nothing blocking.

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% with 9 documented locator parameters (id, name, role, label, etc.), so the schema carries the semantics. The phrase 'an identified ... node' hints that identification is a prerequisite but adds no detail about which locator takes precedence.

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 (expand) on a specific resource (native Accessibility/UI Automation tree node or disclosure control) plus the outcome (reveal its children). An agent can immediately distinguish it from ui_collapse, though the sibling is never named explicitly.

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?

'Use this to expand...' plus 'Inspect the current element first' gives a precondition but no explicit when-not guidance or named alternative (e.g. ui_collapse, or ui_find when the element isn't yet identified). Usage is implied rather than spelled out.

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