tap_element

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It reveals that multiple matches are resolved via an index, that 0 means the first match, and that on error the tool returns the list of matches for refinement. This is useful behavioral context beyond the raw operation.

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?

Three short sentences, each adding distinct value: the main operation, the index disambiguation, and the error behavior. It is front-loaded and has no redundant 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?

The tool has an output schema, so return-value details are not required, but the description leaves out serial and does not specify matching semantics (exact vs. substring) or dependency on screen state. For an action tool with no annotations and zero schema descriptions, these are meaningful 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 description coverage is 0%, so the description must compensate. It explains text, resource-id, class, and index semantics, but omits the 'serial' parameter entirely and does not clarify how multiple selector parameters combine or match. This leaves a notable gap for correct invocation in multi-device scenarios.

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 action and resource: tapping a UI element based on text, resource-id, or class. It also explicitly differentiates itself from the separate find_element + tap workflow, so an agent can cleanly distinguish it from sibling tools.

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?

It clearly says this is a combined search-and-tap operation and that no separate find_element + tap with coordinates is needed. This gives an alternative comparison, though it does not explicitly state when not to use the tool, so it stops short of full when/when-not guidance.

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