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

The description significantly exceeds annotation coverage by stating 'no auth, no state changes, no charges.' It also discloses a behavioral limitation: availability is surface-specific and does not guarantee account eligibility or remaining credits. This adds valuable context beyond the readOnly and idempotent hints.

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 a single, information-dense sentence. Every clause adds value: the verb, resource, scope, safety guarantees, and limitation. It is well-structured and front-loaded with the core purpose.

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?

Given the tool's simplicity (one optional parameter), strong annotations, and existing output schema, the description covers all essential aspects: what it lists, its read-only nature, auth requirements, and a key limitation. No critical information is missing for understanding how to invoke it.

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 input schema already provides a clear description for the single 'surface' parameter with examples. The tool description does not add any parameter-specific details, but because schema coverage is 100%, the description is not required to compensate. Baseline of 3 is appropriate.

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 clearly states the tool's function: 'List public Cannon Studio model availability by product surface.' It uses a specific verb and resource, and the scope is defined. However, it does not explicitly differentiate from sibling tools like list_capabilities or list_offerings, relying on the unique term 'model availability' to imply distinction.

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 no explicit guidance on when to use this tool versus alternatives. It mentions a surface filter and a caveat about eligibility, but does not state scenarios like 'use this before generating a request' or compare against sibling list tools. The usage context is implied rather than stated.

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