tap

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

No annotations are provided, so the description carries the full behavioral burden. It only reveals that the index comes from the last get_screen listing; it does not disclose potential side effects of tapping, required device state, failure conditions, or whether this can trigger consequential actions on the target device.

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?

Two sentences, no filler, and the core action is front-loaded in the first sentence. The second sentence reinforces the critical input source without repeating schema information.

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 is enough to attempt a basic tap, but it omits the meaning of the 'device' parameter and gives no guidance on when to prefer the alternative tap tools. Even with an output schema present, the missing device semantics and usage boundaries leave a significant gap for a device-control tool.

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 usefully explains that 'index' is the element number from get_screen, but it says nothing about the 'device' parameter, leaving its meaning and when to set it opaque.

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: 'Tap an element by its number from get_screen.' It clearly differentiates from sibling tap tools like tap_text and tap_coordinates by anchoring the index to a get_screen listing.

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 provides clear usage context: use the index from the 'last get_screen listing,' and calls this 'the normal way to tap.' However, it does not explicitly contrast itself with tap_text or tap_coordinates, so it stops short of full when-not guidance.

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