get_current_focused_nodes

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

With no annotations provided, the description carries the full burden. It states the tool 'returns a list of UI nodes', implying a read-only operation, but does not disclose limitations (e.g., behavior when nothing is focused, or whether an accessibility service is required). This is adequate for a simple query but leaves some behavioral context unspecified.

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?

The description is a single concise sentence that states the core purpose upfront. It wastes no words and is appropriately sized for a simple tool.

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?

For a parameterless read-only tool with no output schema, the description adequately covers what the tool does. It could clarify the expected output format or the meaning of 'focused', but given the simplicity and the sibling context, it is reasonably complete. The lack of explicit differentiation from get_current_ui_labels is a minor omission.

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?

The input schema has zero properties and schema coverage is trivially 100%. The description explicitly notes 'No parameters are required', which is consistent but redundant. Since there are no parameters to explain, the baseline 3 applies—the description adds nothing 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 ('Returns'), a clear resource ('list of UI nodes'), and context ('currently focused on the connected Android device screen'). This clearly differentiates it from sibling tools like get_current_ui_labels (which returns labels, not nodes) and input_* tools (which perform actions).

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 provides no guidance on when to use this tool versus alternatives. It does not mention get_current_ui_labels or any other sibling, nor any exclusions or prerequisites. A tool like get_current_ui_labels may be similar but the description gives no hint about choosing between them.

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