startRecording

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

Annotations only declare the generic non-read-only, non-destructive, closed-world profile. The description adds real behavior: capture starts asynchronously on return, pointer is recorded as data by default so exports draw a clean cursor and zooms, webcam becomes picture-in-picture, icon hiding follows the user's Record mode setting, and Linux delegates source choice to the OS picker. It omits error/permission behavior, keeping it short of a 5.

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?

Front-loads the core action and target in the first clause, then layers workflow and behavioral detail. Four sentences with no filler, though the webcam/icons/Linux sentences are informative rather than essential to invoking the tool.

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?

With no output schema, the description correctly states the return behavior ('Returns once capture has started') and explains the follow-up action. Combined with a fully documented 6-parameter schema and annotations, an agent has enough to call it correctly; only error/failure handling is unaddressed.

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%, with cursor defaults, window-over-display precedence, and display indexing all documented in the schema, so the baseline is 3. The description's only added semantic is the preference note that window capture avoids capturing anything else on the desktop – useful, but marginal against a fully documented 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?

States a specific verb+resource ('Start recording one window ... or one display') and immediately scopes the target. An agent can distinguish it from stopRecording and listSources without opening any schema.

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?

Gives the workflow explicitly: 'Returns once capture has started; then drive the app and call stopRecording', naming the sibling to call next. It also flags the Linux picker dependency. It does not state when-not-to-use, but there is effectively no competing start-recording tool, so guidance is clear.

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