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

Annotations already mark readOnly/openWorld/non-destructive, and the description adds substantial behavioral context beyond them: results reflect the catalog 'hoje' (today), are sorted by frequency, and the SRD note instructs the agent to offer mixed-breed instead of claiming no pets exist. This edge-case heuristic directly changes agent behavior and is exactly the kind of disclosure that helps.

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 sentences, each earning its place: purpose and ordering, when to use, and the SRD fallback heuristic. Core information is front-loaded and there is zero filler or redundancy.

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 one-optional-parameter list tool, everything an agent needs to call it correctly is present: purpose, usage triggers, ordering, slug semantics for the next call, and the empty-result edge case. An output schema exists so return shape needs no prose, and annotations cover the safety profile.

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% — the `species` parameter already documents accepted values ('dog'/'cachorro' or 'cat'/'gato') and its null default. The description adds nothing about the parameter, but with high schema coverage the baseline of 3 applies and the schema adequately carries that burden.

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 names a specific resource (breeds with pets in the catalog), a clear operation (listing, per the title 'Listar raças'), and precise scoping: results are ordered most-common-first and include slugs for the `breed` parameter. None of the nine sibling tools cover breeds, so it is cleanly differentiated.

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 states explicit usage triggers: 'Use antes de filtrar por raça e quando perguntarem quais raças existem' (use before breed filtering and when asked which breeds exist). It does not name explicit alternatives or when-not-to-use, but no sibling tool overlaps with the breed resource, so exclusions are less critical.

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