list_model_capabilities

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

With no annotations, the description carries the full burden here. It discloses that the tool is a pure local query with no API call and no cost, making its read-only, non-destructive behavior clear. It does not describe exact output formatting or pagination, but that is a minor gap for a simple lookup tool.

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?

The description is compact yet information-dense: it states the resource, the supported capability dimensions, the local/non-charging property, and the two main lookup modes in two sentences. No tautology or 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?

All four parameters are optional, and the description still covers the default behavior of returning all capabilities, explicit model lookup, reverse lookup for restrictions, and the split between image/video. For a static catalog query with no output schema or annotations, this is complete enough for an agent to call it correctly.

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 the baseline is 3. The description adds meaningful context beyond the schema by explaining the 'reverse lookup' semantics for aspect_ratio/size and by giving concrete examples like resolution and ratio formats. This clarifies intent rather than merely repeating property names.

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 uses a specific verb+resource ('查询...能力清单') and clearly states the scope: image/video resolutions, aspect ratios, and durations. It also distinguishes itself from generation tools and similar capabilities by emphasizing '纯本地查询，不调用 API、不收费'.

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 gives explicit usage patterns: exact model lookup via the 'model' parameter, or reverse lookup via aspect_ratio/size/resolution to find available models. It does not explicitly name sibling alternatives or exclusion conditions, so it stops just short of complete routing guidance.

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