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

Annotations already cover read-only, idempotent, and non-destructive behavior, and the description adds real value on top: the scope of the result ('its own and every other brain on the account'), the return shape ('each with the voices that share it'), and cost ('Free'). It does not cover pagination or ordering, but the added context is substantive.

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?

The leading clause is well front-loaded, but the remainder is a long conceptual digression about brain-sharing tradeoffs that reads like rationale rather than operational guidance. For a one-parameter list tool this is more text than the task requires.

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 full annotations and no output schema, the description carries the burden of describing what comes back, and it does so ('its own and every other brain on the account, each with the voices that share it'). The unexplained profile_id parameter is the main remaining gap.

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% and the single parameter (profile_id, uuid) is never mentioned in the description. 'This voice' loosely maps to profile_id, but nothing clarifies that this is the profile identifier or its format, so the description fails to compensate for the schema gap.

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 first clause states a clear verb and resource ('List the Voice Brains this voice may use') and scopes the result to the voice's own brain plus every account brain. The contrast with the sibling set_voice_brain is inferable but never stated, so differentiation relies on the agent's own reasoning.

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 description explains what brains are and how sharing affects novelty checks and what_next, which implies this is a discovery/inspection call before setting a brain, but it never states when to call it versus alternatives. Usage is left to inference.

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