get_asset_thumbnail

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower — yet the description adds real behavioral context: `has_thumbnail` is a class-membership test, no image bytes are returned at all, and ambiguous name resolutions are surfaced in `ambiguous_matches` with first-hit-wins semantics. That is exactly the kind of non-obvious behavior an agent would otherwise get wrong.

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 purpose, then the critical warning, then routing, then resolution, then return shape — a sensible priority order. Minor redundancy: the prose already mentions resolved path, class and loaded state, which the Returns block then repeats field-by-field (justified only because there is no output schema).

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 inlines the full return shape including optional fields, and it closes the biggest comprehension gap (thumbnail capability vs rendered thumbnail). An agent has everything needed to call it correctly and interpret the result.

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?

Single parameter with 100% schema description coverage, so baseline is 3. The description adds meaning beyond the schema by spelling out the resolution algorithm and the `ambiguous_matches` fallback behavior when a name is not unique — useful, though the schema already carries the essential 'exact name vs full package name' contract.

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 (report) and resource (asset thumbnail capability) with the exact returned fields, and immediately names the sibling tools (generate_asset_thumbnail, capture_viewport) that actually render. The explicit warning that `has_thumbnail` is a class test rather than a byte lookup prevents the single most likely misread of this tool.

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?

Explicitly routes the agent: 'To actually see something rendered, use generate_asset_thumbnail or capture_viewport.' It also states the resolution precedence (full package name first, then /Game-only exact-name scan) so the agent knows what input form reaches outside /Game and how to interpret fallback hits.

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