android_ui_click

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

Annotations already supply destructiveHint:true, readOnlyHint:false, and idempotentHint:false, so the safety profile is covered. The description adds a non-obvious behavioral trait: if the matched element is not clickable, the tool falls back to the nearest clickable ancestor. This is genuine context an agent cannot infer from the annotations or schema alone. No contradiction with annotations exists.

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?

One tightly-written sentence with the action verb ('Click') front-loaded, followed by the selection scope ('Nth accessibility element matching a selector') and the key fallback behavior ('nearest clickable ancestor'). Every clause earns its place; there is no filler or repetition of schema or annotation content.

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?

The description covers the core action and the most important behavioral nuance, but the tool has 13 optional, undocumented parameters and no output schema. It leaves unanswered questions an agent will face when invoking it: what happens on no match, whether any result is returned, whether the tool waits for UI stability, and how filters combine. For a tool of this complexity, additional guidance would meaningfully improve call success.

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 0%, so the description must compensate for 13 undocumented parameters, but it only loosely maps 'Nth' to the index field and 'selector' to the filter fields generically. It does not explain how multiple selector fields combine (AND vs OR), which fields caseSensitive applies to, the meaning of enabled/visible/editable as filters, or what happens when no selector is provided. With 13 parameters, this is insufficient.

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 states a specific verb ('Click'), a specific resource ('accessibility element'), and a distinguishing selection mechanism ('matching a selector', 'Nth'). The 'nearest clickable ancestor when necessary' clause further separates it from coordinate-based clicks like android_tap and from read-only query tools like android_ui_find. An agent can tell exactly what this tool does and how it differs from siblings.

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 usage context: this is the selector-based clicking tool rather than a coordinate-based tap (android_tap) or a pure query tool (android_ui_find). However, it never explicitly names alternatives, states when to prefer this over android_tap/android_ui_find, or gives exclusion conditions such as 'use this only when you have an accessibility selector rather than screen coordinates.' The guidance is implied, not stated.

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