start_capture

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

No annotations are provided, so the description carries the full burden. It discloses platform dependency and target format but lacks information on side effects, permissions, or whether the capture is synchronous. Important behavioral traits are missing.

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 sentences, each adding unique value. The first sentence states purpose, the second explains parameter details and platform behavior. No redundant or unnecessary information.

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?

The description covers parameters and platform specifics, but lacks details on return value, error handling, session lifecycle, and whether multiple sessions can run concurrently. For a session-based tool with no output schema, this is incomplete.

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?

With 0% schema coverage, the description compensates well by explaining 'mode' enum values and 'target' types with examples. It adds meaning beyond the schema, though it could clarify that 'target' is only relevant for 'window' mode.

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 'Begin a screen-capture session' with a specific verb and resource. It distinguishes from sibling tools like 'capture_now' and 'stop_capture' by implying a session-based operation.

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?

Provides good guidance on mode and platform constraints (fullscreen universal, window Windows-only with target). However, it does not explicitly compare to sibling tools or specify when to use this tool versus alternatives like 'capture_now'.

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