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

With no annotations provided, the description carries the full disclosure burden and does well: it states idempotency for on/off, discloses that rotate disables auto-rotation, and describes the return payload (ok, action, screenState, orientation?). This is genuinely useful behavioral context beyond what any annotation could summarize. Minor gap: doesn't note whether screen power operations require wake lock or affect ongoing tests, but the core behaviors are transparent.

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?

Three sentences with zero redundancy. Each sentence earns its place: one defines the overall scope, one enumerates the three actions with their behavior, and one states the return payload. Front-loaded with the core purpose and immediately actionable detail.

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 3-parameter tool with full enum coverage and no output schema, the description is quite complete. It covers the action semantics, the conditional parameter relationship, the auto-rotation side effect, and the return shape. It's slightly weaker on failure-mode context (e.g., what happens if device asleep during rotate, or network/permission errors), but for this simplicity level the description is sufficient.

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% and enums cover both action and orientation constraints. The description adds meaningful semantics beyond the schema: it clarifies the conditional requirement that orientation is required when action=rotate and ignored otherwise, and explains the actual effect of each action value (wake vs sleep vs orientation change). This adds real value above the raw 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?

The description uses a specific verb (Control) with a clear resource (device screen power and rotation) and enumerates all three actions (on/off/rotate) with precise behavior for each. It clearly distinguishes from sibling device_* tools like device_battery, device_screenshot, and device_toggle_wifi since it's specifically about screen power and orientation.

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 what each action does in detail, including idempotency behavior and side effects (auto-rotation gets disabled for rotate). However, it doesn't explicitly say when to prefer this over alternatives, nor when NOT to use it. For a device-control tool with no natural sibling conflict, the practical guidance is embedded but not explicit about exclusions or prerequisites (e.g., requiring a launched session).

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