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

Annotations already declare readOnlyHint and idempotentHint, so the safety profile is covered; the description goes beyond that by disclosing the return shape (facet counts for collections/themes/moods/forms plus a ranked poem index) and that results are 'best first'. It says nothing about result caps or auth, but with annotations present that gap is minor.

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 the 'Start here' directive, and each sentence carries distinct information (entry point, return contents, filtering/paging). Slightly redundant between the facet list and the filter sentence, keeping it off a 5.

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?

With an output schema present, return values need not be spelled out, and the description still covers entry-point intent, filtering, sorting default, and paging. Nothing critical is missing for correct invocation, though routing to the sibling lookup tools is unaddressed.

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%, so the schema already documents all seven parameters including sort values and limits. The description only restates the filter dimensions and paging, adding no syntax or format detail beyond the structured fields, so baseline 3 is appropriate.

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 concrete verb+resource (shows shelf facets and an index of poems) and adds a useful scope signal with 'Start here', which frames it as the browse entry point. It does not explicitly contrast itself with search_poems or get_poem, so the sibling distinction is left to inference.

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?

'Start here' is an explicit usage cue, and the description tells the agent it can filter by theme/mood/form/collection and page with offset. It stops short of naming when NOT to use it (e.g. keyword lookup should go to search_poems, single poem to get_poem), so there is no exclusion guidance.

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