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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds the return statuses and failure reason, but the api_key requirement is already present in the schema. It does not go beyond annotations to describe rate limits, errors, or side effects.

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, front-loaded sentence that conveys the core purpose and a required-auth caveat without wasted words. It fits the tool's simplicity well.

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?

Since there is no output schema, the description correctly communicates the status values and failure reason. However, it omits error cases, behavior for invalid api_key or unknown avatar_id, and the intended workflow (e.g., polling after create_avatar). For a simple read tool this is acceptable but not fully complete.

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 50%: api_key has a description but avatar_id does not. The description adds context that the avatar must be one you created, which clarifies avatar_id ownership, but it does not define the ID format, how to obtain it, or what happens when it is invalid. The improvement over the schema is marginal.

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 a specific verb (returns) and resource (status of your own avatar), and enumerates the return values (preparing / ready / failed and failure reason). This distinguishes it from sibling tools like list_avatars or delete_avatar even without naming them.

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?

No explicit guidance about when to call this tool versus alternatives is provided. It does not mention using it after create_avatar to poll readiness, nor contrast it with list_avatars for enumerating avatars. The status values imply polling, but that is left to inference.

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