pinch

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

With no annotations, the description should disclose behavioral traits. It explains the zoom direction but does not mention side effects (e.g., does it trigger browser zoom?), coordinate validity, or step increments. More detail on execution behavior is needed.

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 sentences with key information front-loaded: 'Simulate pinch zoom' and direction logic. No wasted words, structure is optimal.

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 the tool's complexity (gesture simulation with two points) and no output schema, the description covers core logic. However, it could mention execution details like step size or how the gesture is simulated over duration, though duration is in schema.

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 baseline is 3. The description adds value by explaining the relationship between startRadius and endRadius for direction, which clarifies parameter semantics beyond schema 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?

The description clearly states the tool simulates pinch zoom with two touch points converging or diverging. It specifies the direction of pinch in/out based on radius comparison, distinguishing it from other gesture tools like swipe or double_tap.

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 for pinch zoom gestures but does not explicitly state when to use it versus alternatives or provide exclusions. It lacks guidance on context or prerequisites.

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