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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds genuine non-obvious context the annotations cannot: that a 'Ready' status means prepared, not that a speaking test was verified — a real interpretive trap for an agent consuming the status field.

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 short sentences with zero filler; the returned-fields list is front-loaded and the 'Ready' caveat follows immediately as the one piece of clarifying nuance. Nothing can be trimmed 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 usefully sketches the return surface (voice, settings, active version, preparation status), which partly covers the gap. However, it says nothing about the two required parameters or the not-found/error behavior an agent would need before calling.

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 description coverage is 0%, so the schema only gives raw types (workspaceId pattern; characterId is a bare $ref to it). The description never mentions either parameter, their scoping role, or what a characterId denotes, so it fails to compensate for the coverage gap even though the names are fairly self-explanatory.

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 (read) plus the resource (an avatar) and enumerates the payload it returns (voice, settings, active version, preparation status), so the agent knows this fetches a single avatar rather than listing them. It does not name the sibling it contrasts with (list_live_avatars / prepare_live_avatar), leaving that distinction to inference.

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 single-avatar framing implies 'use this when you have a characterId and want one avatar's state', contrasted against the sibling list_live_avatars. But there is no explicit when-to-use, when-not-to-use, or prerequisite statement (e.g., whether the avatar must exist or be prepared first).

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