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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so safety is covered. The description adds meaningful behavioral context beyond that: it discloses the response shape (up to 8 poems, with line counts, opening lines and links) and explicitly warns that the 'what the poem feels like' sentence is generated rather than the poet's words, which is an important honesty cue for downstream use.

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?

A single front-loaded sentence that starts with the core purpose before enumerating the payload. It is dense and slightly run-on with nested parentheses, but every clause carries information about the return value rather than filler.

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 no output schema, the description carries the burden of describing returns, and it does so thoroughly. The main gap is the 'up to 8 poems' truncation: it does not say how to retrieve the remaining poems or what happens with an invalid slug, which matters for a collection that may hold more than eight.

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 coverage is 100%, so the slug format and pattern are already documented in the schema. The description still adds value by stating the provenance of the slug (library_guide or list_collections), which the schema does not say. That goes beyond the baseline 3 for high-coverage schemas.

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 opens with a specific resource and scope: 'One collection by its slug', and immediately enumerates the payload (title, introduction, link, poems). It is clearly distinguishable from list_collections (which returns many) and get_poem (which returns a single poem). It lacks an explicit verb like 'retrieve', but the intent is unambiguous.

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 names where the required slug comes from ('from library_guide or list_collections'), which implicitly routes the agent through those tools first. However, it never states when to prefer this tool over alternatives or what to do if the slug is unknown or invalid, so usage is implied rather than prescribed.

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