glass_gesture

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

The description discloses that multi-touch isn't available on every backend and that it returns a clear Unsupported error where unsupported, which is valuable beyond the annotations (which declare only safety hints). It also explains the timing model (all down at t=0, up at duration_ms) and the 'held pointer' behavior, adding behavioral context that helps the agent anticipate results. The annotations don't specify these runtime behaviors, so the description fills a real gap.

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 concise and information-dense, front-loading the core action and mechanics in the first sentence, then adding gesture examples and a critical limitation note. Every sentence adds non-redundant value; there's no filler or repetition of schema details. It's well-structured for quick scanning by an agent.

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 output schema and a moderate-complexity parameter set (only two parameters), the description covers the essential semantics: pointer segments, gesture types, timing, and backend limitations. The only minor gap is that it doesn't explicitly state the default duration_ms, but that's in the schema description. Overall, an agent has enough to call it correctly without missing critical behavior.

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 schema covers the parameters thoroughly, but the description adds glossary-level meaning: it defines what a 'from==to pointer' means (held), and clarifies how the pointer count maps to gesture types. It reinforces window-relative coordinate semantics already in the schema, and explains the duration default implicitly by describing the timeline. Since schema coverage is 100%, the description's additional gestures and examples go beyond repetition, earning a 4.

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 states a specific verb ('perform'), a precise resource ('multi-touch gesture'), and enumerates pointer count and segment mechanics. It lists concrete gesture patterns (pinch, rotate, swipe, hold), which clearly distinguishes it from single-pointer tools like glass_drag and glass_click, and from other input tools such as glass_key or glass_type.

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 explains the gesture mechanics and provides examples of when to use each pattern (pinch, rotate, swipe), giving clear context. It doesn't explicitly say when NOT to use this tool versus alternatives, but the detailed gesture-specific guidance implies usage for multi-touch scenarios, leaving no ambiguity for common cases.

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