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

Goes well beyond the annotations by disclosing that real key events are synthesized so validation handlers fire, that success is confirmed by reading the control back, and it decodes the three result shapes (verified:true, input_not_applied, verification:'unavailable'). It also names the Accessibility permission prerequisite and a probable cause (window not frontmost) for failure.

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?

Front-loads the action, then the mechanism, then the result contract, then the permission prerequisite. Every clause carries information an agent needs, including the error-code decoding, with 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?

With no output schema, the description correctly takes on the burden of explaining return values and their meaning, which is exactly the missing piece for a UI-automation tool. It covers mechanism, verification, failure modes and permissions, leaving nothing an agent needs in order to call it correctly.

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 coverage is 100%, so both parameters are already documented, and the description's 'focuses element_ref first' essentially restates the schema's 'Optional; focus this element first.' It adds nothing new about text encoding, multiline input, or keystroke timing, so the baseline of 3 applies.

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 and resource ('Types text into the focused control'), and the parenthetical clarifies the focus-then-type behavior. It is clearly distinguishable from siblings such as ui_keystroke and web_type 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 a clear usage context: type into the already-focused control, or supply element_ref to focus first. It never names the alternative tools (ui_keystroke for key combos, web_type for browser fields) or states exclusions, so an agent must infer the boundary itself.

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