tap

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

With no annotations, the description carries the full burden. It states the core action but does not disclose side effects (e.g., triggering a UI event), whether it waits for completion, or any error conditions. For a simple tap, this is minimal but acceptable; it adds no context beyond the literal action.

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 a single, efficient sentence with zero unnecessary words. It front-loads the action and coordinates, making it immediately scannable and memorable.

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 simple tap tool with two required numeric params and an optional device selector, the description is sufficient for an agent to call it correctly. No output schema exists, and the action is straightforward; nothing essential is missing.

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 schema lists x and y as plain numbers with no description, while the description clarifies they are pixel coordinates on the screen, adding meaningful context. The optional serial is already described in the schema. The description compensates for the low schema coverage of the required parameters.

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 clearly states the action ('Tap') and the resource ('screen') with specific coordinates. It distinguishes from siblings like swipe and long_press by implying a discrete, single touch event. The purpose is unambiguous and easy to parse.

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?

There is no guidance on when to use tap versus alternatives such as swipe, long_press, or press_button. The description provides no context about prerequisites, scenarios, or exclusions, leaving the agent to infer usage from the name alone.

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