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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so safety is covered. The description adds genuine behavioral context the annotations lack: result ordering (newest first), the account-scoped result set, and the fact that public characters are resolvable by handle elsewhere but absent here.

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?

Three short sentences, front-loaded with what is listed and in what order, then how to use the handle, then the scope caveat. No redundant restatement of the title or schema.

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?

There is no output schema, but the description enumerates the returned fields and ordering, and the two input parameters are fully documented in the schema. An agent has everything needed to call it and interpret the response.

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 100% and both parameters (limit with default 50 and max 200, cursor referencing next_cursor) are documented there. The description adds nothing about paging or limits, so this is the standard baseline-3 case where the schema does the work.

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 and resource ('List the account's saved characters'), the ordering ('newest first'), and the exact fields returned (handle, name, image, voice). It also distinguishes these from other users' public characters, which are addressable by handle but not listed, separating it from sibling create_character/delete_character.

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?

It gives an explicit next-step instruction ('Put @handle in a generate prompt to include the character') and a scope exclusion ('other users' public characters ... are not listed'), which tells the agent when this tool's output will and won't be complete. It never names a sibling alternative for finding public characters, so it stops short of a full routing rule.

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