ui_tap_element

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

The description discloses behavioral traits beyond annotations: the immediate-tap side effect and the nearest-input-field smart matching for labels. However, readOnlyHint=false already signals mutation, so this isn't adding safety-critical info. It doesn't disclose what happens on no-match (error? no-op?), or whether the tap occurs after a wait/scroll. openWorldHint=true suggests dynamic UI but that's already in annotations.

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 sentences, concise and front-loaded with the core verb+resource. Every sentence conveys meaningful info. Could arguably add when-no-match behavior but the current content is efficient. No wasted words.

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?

There is an output schema present, so return-value explanation isn't required. However, the tool has 8 parameters and behaves on dynamic UI (openWorldHint). The description doesn't address multi-match handling (index parameter semantics beyond schema), timeout/retry behavior, or what happens when no element is found. For a tool that combines find+tap with smart matching, it's adequate but has notable gaps.

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 the schema documents all 8 parameters. The description adds semantic value by explaining the preferInput behavior (nearest input field when targeting a label), which enriches understanding of the preferInput and text parameters beyond their schema descriptions. Good delegation to schema plus contextual highlights.

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 what the tool does: find a UI element by text, resource ID, class name, or content description, and immediately tap it. It also adds a smart behavior (nearest input field for labels). While it distinguishes from ui_find_element (which likely just finds without tapping), it doesn't explicitly name siblings, hence 4 not 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?

The description implies this is used when you want to find and tap in one step, and the 'nearest input' behavior suggests when targeting labels. However, it doesn't explicitly state when to prefer ui_tap_element over ui_find_element+separate tap, nor when not to use it. Usage context is implied but not articulated with exclusions or alternatives.

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