open_camera

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

With no annotations, the description carries the burden. It discloses platform-specific behavior, the fact that no package/bundle ID is required, and the self-timer snapping behavior (e.g., ASUS/Samsung values). This provides meaningful transparency beyond the schema, though it doesn't cover side effects like permissions or errors.

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 well-structured with a brief intro, platform note, then Args list. Every part is useful and avoids redundancy. It is somewhat long but appropriate for the complexity of the parameters, and the formatting improves scannability.

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, the description covers all three parameters and provides platform-specific implementation details. With an output schema present, return values need not be explained. Missing edge cases like permissions or error handling are minor gaps given the scope.

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 fully compensates. It explains the device format (ADB serial or ios:<udid>), enumerates all mode values with their meanings, and describes timer_s supported values and snapping behavior in detail. This adds substantial meaning beyond the bare schema.

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 'Open the platform camera app in a specific mode,' which identifies the exact verb and resource. It differentiates itself from sibling tools like launch_app by specifying the camera app and modes, and the details of Android vs. iOS behavior further distinguish it.

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 gives implementation context (Android launcher/UI automation vs iOS Camera bundle/WDA) and notes that no package or bundle ID is required, which indirectly implies how this differs from launch_app. However, it does not explicitly state when to use this tool over alternatives or provide exclusions, so usage guidance is mostly implied.

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