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

No annotations exist, so the description carries the full burden. It discloses that a single complete record is returned (not a list or partial view) and the read-only nature is implied by 'Retorna', but nothing is said about authentication, not-found behavior, or whether the slug is case-sensitive.

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 with no filler; the resource and the lookup key come first. It is tersely complete rather than padded, though it stops short of any routing information that would have earned 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?

For a one-parameter getter with full schema coverage and no output schema, the description covers the essential contract: full record, keyed by canonical slug. Only edge behavior on an invalid or unknown slug is left undefined, which is a minor gap at this complexity level.

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 there is only one parameter, so the schema already documents the slug. The description adds only the qualifier 'canônico', which usefully signals that non-canonical or alias slugs are not accepted, but adds little beyond that.

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 states a specific verb and resource ('Retorna o registro completo de uma obra') and narrows the lookup key to the canonical slug. It is clearly distinguishable from search_books/list_books, though it never names those siblings to make the distinction explicit.

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?

Usage is only implied: 'pelo slug canônico' tells the agent it must already hold an exact identifier, which indirectly rules out discovery use cases. There is no explicit 'use this when you have a slug, use search_books when you don't' guidance or any mention of what to do on a miss.

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