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 discloses coordinate units (screenshot pixels) and long-press behavior, but omits side effects, failure behavior when targets are missing, and whether it waits for UI changes.

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?

One tightly written sentence with the primary action and modifiers front-loaded. Every clause adds targeting or long-press 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?

For a 6-parameter UI action with no annotations and no output schema, the description covers targeting well but is thin on operational behavior and validation. It does not say that one targeting mode is required, how conflicts are resolved, or what happens on failure.

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 67%, with x/y undocumented in the schema; the description compensates by defining x/y as screenshot pixels and framing target selection as ref/text versus point. It still leaves precedence between ref and x/y, and the required pairing of x/y, unstated, while serial is only covered by 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 names a specific verb (Tap) and the exact target types: an element by ref or visible text, or a point by x/y. This clearly distinguishes it from siblings such as phone_swipe, phone_scroll, phone_type, and phone_key.

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 explains the three targeting modes and the optional long-press flag, which is useful invocation guidance. However, it gives no explicit when-to-use guidance, no alternatives, and no prerequisite such as needing a prior phone_look to obtain refs.

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