Tap the screen

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

Annotations declare the safety profile (readOnly=false, idempotent=false, destructive=false, openWorld=false), and the description adds a genuinely useful runtime behavior: input events are silently dropped while the display is off, so key_event WAKEUP must precede the tap. It also prescribes a screenshot-verify loop, though it does not discuss failure modes such as taps landing outside the visible area.

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 action and its raw equivalent are front-loaded in the first clause, followed by coordinate sourcing, verification, and the wake precondition in descending order of importance. Every clause carries information; there is no 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?

With no output schema and annotations already covering the safety profile, the description supplies the remaining essentials: exact command semantics, coordinate provenance, the screen-off precondition, and the verification loop. An agent can call this correctly without opening any sibling tool definition.

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 baseline is 3, but the description goes further by telling the agent where valid x/y values come from (get_ui_hierarchy bounds vs. get_device_info screen_size), which is actionable provenance not present in the schema. It does not add anything new for the optional `device` parameter.

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 names a specific verb+resource and pins the exact underlying operation (`input tap X Y`), so the agent knows precisely what will happen on the device. It is clearly distinguishable from siblings like swipe, type_text, and key_event.

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 explicitly routes the agent to get_ui_hierarchy bounds and get_device_info screen_size for coordinates, and to screenshot for post-tap verification, which is strong contextual guidance. It does not, however, state when to prefer swipe or type_text over tap, so the alternative selection is only partly covered.

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