Tap

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

Goes well beyond the annotations by disclosing that rotation is not checked, that a stale screenshot (>120s) is refused, and that a failed verify never converts a performed tap into an error. These are non-obvious behavioral traits an agent needs, and nothing contradicts the annotations.

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?

Front-loaded with the core action, then dense but purposeful sentences covering each mode and the alternative. Slightly packed, but no wasted sentences.

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 tap mutation with no output schema, the description covers coordinate spaces, staleness limits, verification semantics, and the sibling alternative. Complete enough for correct invocation, with only minor gaps around which other alternatives to prefer.

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 100%, so the baseline is 3, but the description adds real meaning: it clarifies that 'screen' is the logical space input tap uses (vs screenshot rescaling) and explains what each verify mode compares. This meaningfully augments the enum descriptions.

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 (tap) and resource (x, y coordinates) with clear scope, and explicitly contrasts itself with the sibling adb_find_and_tap. An agent can distinguish it from the label-based alternative without opening any 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?

Gives explicit conditions for the two coord modes and routes label-based activation to adb_find_and_tap. Clear context for when to use it, though it doesn't address other alternatives like adb_swipe or adb_key.

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