list_characters

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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior, so the description doesn't need to repeat safety. It adds useful context by noting the scope is limited to the authenticated service account and that presigned URLs are included in the response, but it omits details like pagination behavior or sorting semantics, which are only hinted at in parameters.

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 two concise sentences with no redundant words. The core action and scope come first, and the presigned URL note is placed second. Every sentence contributes value, making it well-structured and efficient.

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 simple list operation with no required parameters and full annotations, the description covers the essential purpose and a key response feature (presigned URLs). Pagination and sorting are implied by parameters, and the lack of an output schema isn't critical here given the straightforward list nature. It is nearly complete, though it could explicitly mention pagination or the returned character fields.

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% for all three parameters (limit, nextToken, sortAscending), so the schema already handles parameter documentation. The description adds no further meaning about these parameters; this matches the baseline for high coverage.

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's first sentence uses the specific verb 'Retrieves' with the resource 'a list of characters', clearly distinguishing this from the sibling get_character tool. It also names the scope ('available to the authenticated service account') and mentions presigned URLs, which adds a meaningful resource detail.

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 provides no guidance on when to use this tool versus alternatives like get_character or list_scenes. It implies a list operation through the tool name, but there is no explicit context, exclusions, or mention of sibling tools that could help an agent choose correctly.

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