device_appearance

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

No annotations are provided, so the description carries full responsibility for behavioral disclosure. The description only says 'Set the simulator to light or dark mode' and omits critical details: whether the simulator must be booted, whether the change persists, whether it affects all apps, or if there are any side effects. This is severely lacking for a tool that mutates simulator state.

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 a single, efficient sentence with no redundancy. However, the conciseness comes at the cost of missing important behavioral and usage information. It is well-structured but under-informative, earning a 4 rather than a 5.

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 simple tool with 2 parameters and no output schema or annotations, the description should provide enough context for correct invocation. It fails to mention prerequisites (e.g., simulator must be booted, deviceId must come from a list or earlier tool like simulator_list). Without this, an AI agent may attempt to use the tool incorrectly, leading to errors.

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%: both parameters have clear descriptions in the schema ('Simulator UDID', 'Appearance mode' with enum). The description adds no additional meaning beyond what the schema already provides. Per the rubric, with high schema coverage, a baseline of 3 is appropriate; no extra value is contributed.

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 uses a specific verb 'Set' and explicitly identifies the resource ('the simulator to light or dark mode'). It clearly distinguishes from sibling tools like simulator_boot, simulator_shutdown, and status_bar_override, which have different purposes. The action and resource are unambiguous.

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?

No guidance is provided on when to use this tool versus alternatives. For instance, it does not mention that this tool is for toggling appearance during UI testing, nor does it contrast with tools like status_bar_override which might also affect display. There is no exclusion context (e.g., 'only works on booted simulators').

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