Add a source to a scene

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

Even with annotations (readOnlyHint=false, destructiveHint=false), the description adds meaningful behavioral detail: the source appears live immediately if the scene is active, lands centered by default, and returns the new source_id. No contradictions with annotations.

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?

Four tight sentences, each covering a necessary aspect: purpose, behavior, parameter guidance, follow-up actions, and return value. No redundant or filler content; the most important information appears first.

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?

Despite lacking an output schema, the description explicitly states the return value (new source_id). It covers default scene, live appearance, conditional parameter requirements, default positioning, and reference to related tools. The description is complete for a tool with moderate complexity and good schema coverage.

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?

The schema covers all parameters (100%), giving baseline 3. The description enriches by specifying that device_id and source_type must be passed verbatim from list_devices for cameras/displays/windows, clarifying the relationship between these parameters. This goes beyond the schema's individual descriptions.

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 opens with 'Add a source to a scene', a specific verb+resource statement that clearly identifies the function. It further distinguishes itself from sibling tools by explaining the live behavior, default scene behavior, and post-add positioning via set_source_transform.

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 provides clear context: it defaults to active scene, requires device_id and source_type from list_devices for camera/display/window sources, and directs users to set_source_transform or set_source_shape for further editing. It does not explicitly state when to use this tool over alternatives, but the guidance is sufficiently purposeful.

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