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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so safety is covered. The description adds genuinely new behavior beyond that: the list returns empty (not an error) for accounts without an active Revid plan, which tells the agent how to interpret an empty result. Pagination, ordering, and whether inactive characters appear are still unstated.

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, front-loaded with the core action and followed by the one non-obvious caveat. Every clause earns its place with no filler or restatement of the title.

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 read tool with an output schema (so return shape need not be documented) and strong annotation coverage, the description covers scope, auth context, and empty-state semantics. It is nearly complete, missing only result ordering or whether deleted/inactive characters are excluded.

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 tool takes zero parameters, so there is nothing for the description to disambiguate; the baseline of 4 applies. No parameter text is needed and none is misleading.

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 uses a specific verb and resource ("List saved consistent characters"), scoped to "the authenticated user," which clearly separates it from sibling list_* tools such as list_projects or list_voices by resource noun. It stops short of naming a sibling or contrasting with create_character/delete_character, so it is clear but not fully differentiated.

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?

Usage is only implied: the tool exists to enumerate characters, presumably before referencing one in an episode or for review. There is no explicit when-to-use statement, no mention of when to prefer this over list_presets or list_series, and no prerequisites beyond the plan note.

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