start_recording

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

No annotations are provided, so the description carries the behavioral burden. It usefully discloses that the output is only persisted via stop_recording and that the artifact is a .mov file, but omits whether an in-progress recording is overwritten, whether permissions are required, or what the call returns immediately.

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 short sentences, zero filler, with the core action front-loaded and the dependency on stop_recording stated second. Nothing redundant.

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?

An output schema exists, so return values need not be explained, and the description covers the essential start/stop relationship. It is nearly complete for a two-parameter tool, though it could note error/duplicate-recording behavior.

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 both device_id (Simulator UDID) and codec (enum hevc/h264) are already documented in the schema. The description adds no further meaning about parameter behavior or defaults, making the baseline 3 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 precise verb+resource ('Start screen recording') and explicitly names the paired sibling 'stop_recording', so an agent can distinguish the two without opening either schema. No ambiguity about what the tool initiates.

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 supplies a clear next-step context: recording is only saved by calling stop_recording, which tells the agent this is one half of an ordered workflow. It does not discuss preconditions (e.g., what happens if a recording is already active) or alternatives, but there are no true alternatives among siblings.

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