pinch

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

With no annotations, the description must carry the burden; it does disclose the emulator-only constraint and the centering behavior (handle, "x,y", or screen centre), which is meaningful context beyond structured fields. It stays silent on timing/observation behavior such as max_wait_ms and observe_after, leaving a gap for a gesture tool.

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?

A single dense sentence that front-loads the gesture and effect, followed by the constraint. Every clause contributes information; nothing is wasted.

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?

An output schema exists, so return values needn't be explained, and the gesture semantics plus target formats are covered. But for a 4-parameter gesture tool with no annotations, the unexplained timing/observation parameters leave it short of fully complete.

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 0%, so the description must compensate: it usefully clarifies that zoom takes 'in'/'out' and that target accepts a handle or "x,y" with screen-centre fallback. The remaining two parameters (max_wait_ms, observe_after) receive no explanation, so compensation is only partial.

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 gesture (two-finger pinch) and its effect (zoom 'in' or 'out'), which clearly differentiates it from single-finger siblings like swipe, scroll, and tap. It lacks an explicit contrast statement to those siblings, keeping it just below a 5.

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 'Emulator gRPC only' note is a useful precondition, and the zoom framing implies when to reach for it versus swipe/scroll. However, it never explicitly says when not to use it or names alternatives for zooming, leaving usage to inference.

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