Start Screen Recording

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

The annotation destructiveHint:true already signals potential harm, and the description adds behavioral context: the recording runs in the background, requires an explicit stop, and returns a save path. No contradiction with annotations is present.

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 concise sentences, front-loaded with the action, and no fluff or repetition of schema details.

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 start-recording tool with no output schema, the description conveys the key return value (path), the background lifecycle, and the stop counterpart. The schema covers parameter details, making this description 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?

Input schema covers all three parameters with descriptions (100% coverage), so the description adds little beyond noting the returned path. This aligns with the baseline score of 3.

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 the specific verb 'Start recording' with the resource 'screen of a mobile device,' clearly distinguishing the tool from its sibling mobile_stop_screen_recording, which is explicitly named. It states the action and the object precisely.

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?

It explains that the recording runs in the background until stopped with mobile_stop_screen_recording, giving clear context for when to use this tool and naming its counterpart. It lacks explicit 'when not to use' guidance, but the context is unambiguous.

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