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

Annotations already cover readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is established. The description adds meaningful behavioral context: it returns stable window identifiers and PID/bounds, and it scopes results to top-level desktop windows, which is useful for downstream operations.

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 focused sentences with no filler. The first states the primary use, the second gives the alternative selections. The key user need is front-loaded and 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?

With full schema coverage, an output schema present, and annotations covering safety, the description provides all necessary selection and invocation context. It states scope, output relevance, and alternatives, leaving no critical gap for an agent deciding whether to call this tool.

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% and both parameters are already well documented, with include_monitor explicitly noting its default. The description adds no new parameter-level meaning, so it stays at the baseline for full schema coverage.

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 clearly states the tool's function: discover top-level desktop windows and obtain a stable window id/PID/bounds. It distinguishes itself from ui_snapshot and screenshot-based guessing, making the resource and its scope immediately clear.

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?

The description explicitly states when to use it ('before window_action, screenshot_region or targeted input'), when to use an alternative ('Use ui_snapshot instead when you need controls inside a window'), and expresses a clear preference over screenshot-based guessing. This provides concrete routing among siblings.

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