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

Annotations declare readOnlyHint=false, idempotentHint=false, destructiveHint=false, so the mutation profile is partly covered. The description adds real value by clarifying that the tool is metadata-only, does not download media, and spends no credits, which would otherwise be a serious ambiguity for a create tool on a paid platform. It doesn't state ownership/auth requirements or what happens on duplicate name.

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 tight sentences, front-loaded with the verb and resource, then immediately disambiguating with the crucially negative 'does not generate or download media and spends no credits.' No 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 mutation tool with 10 params at 0% schema coverage and no output schema, the description is too thin to be complete. It clarifies cost/behavior but not parameter meaning, return shape, or authentication. It covers the highest-value ambiguity (credits/media) but leaves the schema without compensating documentation.

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 0% across 10 parameters, so the description must carry the load. It only loosely gestures at 'descriptive fields' and 'optional existing HTTPS media references,' leaving notes, summary, imagePromptAddon, videoPromptAddon, world_id, referenceImages, and imageUrl entire meanings undocumented. That is a substantial gap for a tool with 10 params.

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 (Create) and resource (world asset) and enumerates the six kinds it supports, which maps precisely to the schema enum. It also distinguishes itself from generation siblings by defining itself as metadata-only.

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 says it does not generate or download media and spends no credits, implicitly routing media generation to create_generation_request, but it never names that sibling or states when to use this tool versus fetching/updating an asset. Usage context is implied rather than explicit.

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