Focused control

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

Annotations already declare this read-only, idempotent and non-destructive, so safety is covered. The description adds modest extra value by framing the result as a point-in-time view of the focused control and by offering the unlabeled-control interpretation, but says nothing about behavior when no control has focus or about NVDA needing to be running.

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?

The identity of the tool and the enumeration of returned fields come first, with usage and the diagnostic tip in a short following paragraph. Every sentence carries information and there is 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?

An output schema exists and the description's field enumeration complements it well, so return values are well covered. The gap is preconditions for a focus-dependent read (no focused control, NVDA not attached), which an agent would benefit from knowing before calling.

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?

There is a single optional response_format parameter fully documented in the schema, and the description never mentions it. With 100% schema coverage the baseline of 3 applies; the description adds no output-format guidance of its own.

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 specific verb ('describe') and a precisely scoped resource ('the control that has keyboard focus, as NVDA sees it') and enumerates the returned attributes, so the agent knows exactly what it gets. It implicitly separates itself from navigator-object siblings by scoping to keyboard focus, but never names an alternative, keeping it short of a 5.

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 provides concrete usage framing: answer "where am I?" or debug an unexpected announcement, plus the heuristic that an unnamed button/link is usually unlabeled. There is no explicit when-not guidance or named alternative (e.g. use nvda_get_navigator_object or nvda_inspect_object when nothing has focus), so it stays at 4.

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