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

With only readOnlyHint=false, the description carries most of the burden and does well: it discloses that the operation is free, creates no pixels, and targets the 'primary lane'. It omits what is returned (scene id?) and whether the scene can later be regenerated, so a few behavioral details 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?

Front-loaded with the core definition and cost/behavior facts before the prompt-craft rules. Dense but mostly earning its space; the prompt-style guidance could be trimmed slightly but is actionable rather than filler.

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 creation tool with no output schema, the description explains what gets created, where it lands, and how to write the prompt. The main gap is the return value and the effect of the 'position' parameter on ordering, which is left entirely to the schema.

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 coverage is 100%, so baseline is 3, but the description adds genuine meaning for the most important parameter ('The prompt is the scene's recipe') and specifies the required content ingredients: subject, action, lighting, color palette, mood. It also contributes a strong negative constraint on camera-equipment phrasing, which is real semantic guidance beyond the 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 and resource ('Add a PLANNED scene (storyboard placeholder) to the primary lane') and immediately disambiguates it from generation siblings by clarifying 'no pixels are generated'. An agent can distinguish it from studio.generate_scene and studio.add_scene_from_asset without opening schemas.

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?

Clearly establishes the context of use: a free storyboard placeholder rather than a rendered scene, which implicitly routes rendering requests to studio.generate_scene. It does not name that alternative explicitly or state exclusions, so it stops short of full when/when-not guidance.

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