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

The description discloses that the tool returns a list of built-in and custom personas, providing some behavioral context. However, with no annotations, it does not explicitly state read-only nature, return format, or potential edge cases, leaving some burden unmet.

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 description is a single, front-loaded sentence using a parenthetical for extra detail. Every word earns its place, with no redundancy or filler.

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?

For a zero-parameter listing tool with an output schema, the description adequately covers the essential purpose and content. It could mention ordering or use-case triggers, but those are not critical given the tool's simplicity.

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?

The input schema has zero parameters, so there is nothing for the description to add. The baseline of 4 applies, and the description appropriately avoids stating anything about parameters.

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 description clearly uses a specific verb ('List') and resource ('personas'), and further clarifies scope with 'selectable' and 'built-ins plus your custom personas.' This distinguishes it from the sibling tools (get_balance, humanize) which serve entirely different purposes.

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 phrase 'List selectable personas' implies when to use the tool: when an agent needs to see available personas for selection. However, it does not explicitly state alternatives or exclusions, but given the sibling tools are unrelated, the context is sufficiently clear.

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