Start Screen Recording

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

Annotations only indicate readOnlyHint=false and destructiveHint=false, so the description carries the main behavioral burden. It usefully discloses that recording continues in the background, that it requires a stop call, and that it returns the save path. This goes beyond annotations, though it does not address permissions or concurrent recordings.

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 with no filler. The core action is front-loaded, followed by the key behavioral detail about stopping and the return value. Every sentence earns its place.

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 relatively simple action with no nested objects and no output schema, the description covers the essential behavior: what it does, how it ends, and what it returns. It does not mention prerequisites or failure modes, but those are not critical for invoking this tool correctly.

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 description coverage is 100%, so each parameter (device, output, timeLimit) is already documented in the schema. The description adds no additional parameter meaning beyond confirming a return path, so the baseline 3 is appropriate.

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?

States a specific action ('Start recording the screen of a mobile device') with a clear resource and lifecycle. It also distinguishes itself from the sibling mobile_stop_screen_recording by naming it directly, so an agent can disambiguate at a glance.

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 establishes the operative context: the recording runs in the background until explicitly stopped with mobile_stop_screen_recording. It does not explicitly enumerate when-not-to-use alternatives, but the pairing with the stop tool gives clear usage guidance.

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