Switch browse or focus mode

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

Annotations already declare readOnlyHint=false, destructiveHint=true, idempotentHint=false and openWorldHint=true, so the safety profile is covered; the description usefully adds the real consequence of browse mode (single letters navigate instead of typing) and the downstream effect on nvda_type_text. It does not, however, explain why the call is flagged destructive or whether setting the same mode twice is a no-op, and 'switch between ... like NVDA+space' slightly suggests a toggle even though an explicit mode is required.

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?

Three short sentences that front-load the core action, then the state-check path, then the typing caveat — no filler. The middle sentence is slightly awkwardly ordered (reporters named before the action they support), but 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 annotations plus an output schema available, the description supplies what the structured fields cannot: the user-facing effect of each mode and the cross-tool sequencing with nvda_type_text. The only gap is that it does not clarify that mode is a required explicit target (not a toggle) or what the call returns/raises on timeout.

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%, including a fully documented mode enum and the settle_ms/timeout_ms timing knobs, so the schema carries the parameter burden. The description reinforces mode semantics through the 'before nvda_type_text' rule but never mentions the settle/timeout parameters or their behavior, adding little beyond 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 opens with a specific verb+resource (switch NVDA between browse mode and focus mode) and scopes it to a web page or document, with the 'like NVDA+space' analogy anchoring the exact user-level behavior. It also implicitly differentiates itself from nvda_get_focus and nvda_get_status, which are named as reporters of the mode rather than setters.

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 gives an explicit use condition: switch to focus mode before calling nvda_type_text in a web form when NVDA did not switch automatically — a concrete precondition tied to a named sibling. It also routes the agent to nvda_get_focus / nvda_get_status for reading the current mode, so the read/write split is unambiguous.

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