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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, and the description does not contradict them. It adds content context about the fields but no additional behavioral traits such as pagination, ordering, permissions, or side effects.

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 efficient sentence with a front-loaded resource header and a compact parenthetical field list. It is concise and has no filler, though the phrasing around 'team faces Siren can put in stills' is somewhat awkward.

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-only list tool with an output schema and strong safety annotations, the description is nearly complete. It gives the domain and content, while output format and side effects are already covered by the output schema and annotations.

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 schema description coverage is trivially complete. The parenthetical field list refers to record contents rather than invocation parameters, so there is no parameter meaning the description needed to clarify.

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 is a noun phrase ('The people library') rather than an explicit action statement; it never says 'list' or 'retrieve.' It does provide useful resource detail and distinguishes people from other listable resources, but the operation itself is left to the tool name.

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?

No explicit when-to-use guidance or alternative tools are mentioned. The 'team faces Siren can put in stills' phrasing implies a data-domain use case, but the description does not say when to prefer list_people over add_person, delete_person, or the other list_* siblings.

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