List custom avatars (and their scenes)

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

With no annotations, the description carries the full burden: it does disclose the mode-switching behavior of avatar_id and the voice_kind routing semantics ('user' vs 'library'), which is real behavioral context. However, it never states the operation is read-only/side-effect free, nor mentions pagination, result size, or auth requirements, leaving gaps an unannotated list tool should cover.

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 dense sentences that are front-loaded with the core purpose before moving to id-routing detail; every clause about voice_user_id/voice_id/scene_id earns its place. It is dense but not padded.

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?

No output schema exists, so the description must describe returns, and it does: avatars carry a default voice {id, voice_kind} and scenes expose scene_id. Minor omissions remain (no pagination or error behavior), but the cross-tool id plumbing is complete enough to call the tool 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, but the description goes beyond the schema by explaining the downstream consumption of avatar_id and the voice_kind enum-like semantics for the returned voice object. That added meaning about how ids are used justifies a 4.

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 verb+resource (custom avatars trained in CraftStory) and additionally covers the dual mode where avatar_id returns scenes instead of the list. An agent can distinguish this from list_voices and list_models because the description names the avatar/voice/scene domain explicitly.

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?

Gives clear conditional guidance: omit avatar_id to list avatars, pass avatar_id to list that avatar's scenes, and explains how the returned ids feed create_audio_clip and create_craftstory2_video. It does not explicitly say when to prefer a sibling (e.g. list_voices) over this tool, so it stops short of a full 5.

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