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

Annotations already declare the safe read-only, idempotent, non-destructive profile. The description adds value by disclosing the return fields and clarifying that avatars made in the Vids web app are included, plus the cross-reference for resolving previewMediaId.

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?

Effectively one dense sentence that front-loads what gets listed, then the fields, then the resolution path. No filler, though the nested parentheticals make it slightly packed.

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 carries the return burden and mostly does so by enumerating the fields. It stops short of noting pagination or limits, but for a simple one-param list tool it is close to sufficient.

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 single email param is documented there ('Only this account. Default: every account.'). The description says nothing about the param, so the baseline 3 for high-coverage schemas applies.

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 (list avatars) and enumerates the returned fields (avatarId, name, voice, previewMediaId). It distinguishes itself from other list siblings like vids_list_voices/list_accounts by resource, though it doesn't explicitly name 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 when/when-not guidance against alternatives. The only routing text is a follow-up hint ('see it with vids_get_media' for previewMediaId), which is implied usage rather than selection criteria.

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