mobile_tap

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

With no annotations, the description must carry the full behavioral burden. It only states the action and return type, omitting any side effects, prerequisites, or failure modes. For a simple action like a tap, this is minimal but not entirely absent since it says 'Tap once' and returns JSON.

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 concise and front-loaded with the action, then organized into Args and Returns sections. Every sentence earns its place with no fluff or repetition.

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 covers the essential call details for a simple action, including parameter semantics and return type. It omits contextual info like device readiness or coordinate bounds, but given the presence of an output schema and the simplicity of the action, it is adequate and not overly incomplete.

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 description fully explains each parameter: serialno's source and type, and that x/y are device pixels. This adds substantial meaning beyond the bare schema which only lists types and titles, compensating for the 0% schema description coverage.

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 'tap' with 'once' to distinguish from double tap and long press, and specifies screen coordinates. It clearly identifies the resource (mobile screen) and action, making it distinct 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?

The description provides parameter sourcing guidance (serialno from list_devices) but does not explicitly compare to sibling tools like mobile_double_tap or mobile_long_press. Usage context is implied through the 'once' qualifier, but no direct when-to-use instructions are given.

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