List custom avatars (and their scenes)

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

Annotations already declare readOnlyHint/openWorldHint, so safety is covered. The description adds genuine behavioral context the annotations cannot: the voice_kind-to-parameter mapping and the fact that supplying avatar_id switches the tool into scene-listing mode. It omits return shape/pagination, which for an unpaginated list tool is a minor gap.

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?

Three tight sentences, front-loaded with what the resource is, then the actionable id hand-offs. Dense but every clause carries routing information; slightly heavy on nested parameter names, though none are removable without losing meaning.

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 must carry the return semantics, and it does: avatars, their optional default voice object, and scenes when avatar_id is given. Missing only pagination/format detail, which is minor for a simple list tool.

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% and the schema already documents avatar_id, so the baseline is 3. The description goes beyond it by explaining the mode-switch consequence and how the returned id feeds create_audio_clip and create_craftstory2_video, adding downstream meaning the schema lacks.

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 resource (custom avatars trained in CraftStory) and the sibling model it serves (craftstory-2), plus the dual listing mode (avatars vs. an avatar's scenes). An agent can distinguish it from list_models and list_voices without opening schemas.

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?

Explains how to consume the output — pass the id as avatar_id, route voice_kind 'user' to voice_user_id and 'library' to voice_id in create_audio_clip, and use scene_id in create_craftstory2_video. It does not explicitly say when to prefer this over list_voices/list_models, so there is no exclusion guidance.

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