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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds meaningful behavioral constraints beyond annotations: the city must already be resolved, the tool returns aggregate stats only, and it does not return pets or NGO identities. It also references error behavior for ambiguous or pet-less cities, giving useful operational context.

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 compact and efficient: the first sentence lists the returned metrics and the resolved-city precondition, and the second sentence gives the primary use case and key exclusions. Every clause earns its place with no 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?

Given the tool's low complexity, two parameters, full schema coverage, and presence of an output schema plus safety annotations, the description covers everything an agent needs to invoke it correctly. It states what the stats include, when to use the tool, what it deliberately omits, and the required input precondition.

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 both the city and state parameters thoroughly, including the slug/name format and optional UF. The description reinforces that the city must already be resolved, but it adds little beyond what the parameter descriptions already provide.

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 exactly what the tool returns: catalog counts for one already-resolved city, including pets by species, size, and age, plus adoptions, NGO counts, and common breeds. It also distinguishes itself from siblings by explicitly stating what it does not do (return pets, resolve city names, list which NGOs), making its purpose unmistakable.

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?

The description gives an explicit use case: 'Use para quantos pets tem em X?' and clearly states exclusions: it does not return pets, does not resolve city names, and does not list which NGOs, pointing to the NGO search for that. However, it does not explicitly name the sibling tool for resolving city names or for obtaining pet lists, leaving a small inference gap.

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