get_ui_tree

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

No annotations are provided, so the description carries the full burden. It does disclose useful behavior: the tree lists visible elements and attaches tap indices, which tells the agent the output is actionable. However, it omits read-only/rate-limit characteristics and does not mention that visibility filtering is configurable, leaving meaningful gaps for a tool with zero annotation coverage.

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?

A single front-loaded sentence with no filler, stating purpose and output utility immediately. It is arguably too terse given the tool's 4 parameters and output schema, but nothing in it 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?

An output schema exists, so return-value explanation is not required, and the description correctly signals the actionable index output. It is still incomplete for a tool with this much sibling overlap, since it gives no routing context against get_screenshot or the tap/long_press tools whose indices it feeds.

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 all four parameters carry descriptions, so the baseline is 3. The phrase 'visible elements' loosely maps to only_visible, but the description adds no format or verbosity semantics 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 states a specific verb and resource ('Get the UI accessibility tree') and adds what the result is for ('indices for tapping'), which distinguishes it reasonably well from screenshot-based siblings. It does not explicitly contrast itself with get_screenshot or get_window_size, so it stops short of full sibling differentiation.

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?

There is no guidance on when to use this tool versus alternatives such as get_screenshot (visual) or get_window_size (dimensions), nor any prerequisites stated. The agent must infer the use case from the phrase 'indices for tapping'.

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