tap_text

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

With no annotations, the description carries the full burden, and it does disclose two useful traits: it performs a fresh screen dump (a latency/side-effect cost) unless the previous dump is reused, and it taps the element's centre rather than an arbitrary point. It omits failure semantics (no match found, multiple matches), any permission/accessibility-service requirements, and whether the dump is cached across calls.

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 tight sentences, front-loaded with the core action and the differentiator. Every clause carries information; nothing is redundant or padded.

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 coordinate-free tapping tool with no annotations and no output schema, the description covers the core mechanism and the screen-dump cost, but leaves notable gaps: behavior when no element matches, disambiguation beyond the schema's 'nth', and the meaning of 'exact'. Adequate but not fully self-contained.

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 adds real meaning to 'text' by clarifying it matches visible text, content description, or resource id, which goes beyond the schema's thin 'Label to look for'. However, the 'exact' parameter has no description in the schema and receives no explanation here (exact vs substring matching), leaving one of four parameters semantically unaddressed at 75% 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?

States a specific verb and resource ('Find an element by its visible text, content description or resource id and tap its centre') and immediately distinguishes itself from the sibling 'tap' by framing itself as the robust alternative to coordinate guessing. An agent can route between tap and tap_text without opening either schema.

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?

Explicitly positions this as the preferred over-coordinate approach ('the robust alternative to guessing coordinates'), which tells the agent when to pick it over 'tap'. It also notes the screen-dump behavior. It stops short of stating exclusions or fallback behavior (e.g., what to do when no match is found), so it is clear context but not complete when/when-not guidance.

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