tap_element

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It describes the action (tap) and finding mechanism, but lacks details on permissions needed, error handling (e.g., if element not found), side effects (e.g., UI changes), or performance aspects. This is a significant gap for a tool that interacts with UI elements.

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 two concise sentences that front-load the core action and mechanism, with no wasted words. Every sentence earns its place by specifying the tool's purpose and behavior efficiently.

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?

Given no annotations and no output schema, the description is minimal but covers the basic action. However, for a tool with 3 parameters and UI interaction complexity, it lacks details on return values, error cases, or behavioral nuances, making it adequate but with clear gaps in completeness.

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 100%, so the schema already documents all parameters ('by', 'value', 'device_id') with descriptions and enums. The description adds no additional meaning beyond what the schema provides, such as examples or usage context for the parameters, meeting the baseline for high schema 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 clearly states the specific action ('tap a UI element') and the mechanism ('by its resource-id, text, or content-desc'), distinguishing it from siblings like 'tap' (which lacks the same specificity) and 'tap_and_wait' (which implies additional waiting behavior). It precisely defines the verb and resource with implementation details.

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 implies usage by stating it 'finds the element in the UI tree and taps its center,' suggesting it's for interacting with visible UI elements. However, it lacks explicit guidance on when to use this tool versus alternatives like 'tap' (which might be simpler) or 'tap_and_wait' (for asynchronous interactions), and doesn't mention prerequisites or exclusions.

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