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

Annotations already flag destructiveHint=true and idempotentHint=true, but the description adds meaningful context beyond them: presets are excluded from deletion, past session records persist, and the api_key must come from signup. No contradiction with annotations.

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 compact Japanese sentences that front-load the core behavior and then the key limitations, with zero filler or redundant restatement of the title.

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 simple destructive tool, it covers what can and cannot be deleted, what persists afterward, and the auth requirement. Without an output schema, return behavior is undocumented, but this is a minor gap for a delete operation.

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 schema description but avatar_id does not. The description adds value for api_key (key received at signup), but adds nothing specific about avatar_id beyond what the tool name implies.

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 states a specific verb and resource ('deletes avatars you created yourself') and adds a distinguishing constraint (presets cannot be deleted). This clearly separates it from sibling tools like get_avatar, list_avatars, and create_avatar.

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?

It gives clear context: use on self-created avatars, not presets, and requires the api_key from signup. It doesn't explicitly name alternative sibling tools, but the preset exclusion acts as a clear when-not condition.

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