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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds genuinely useful behavioral context: the guide's content scope and the fact that its Golden Visa guidance reflects the post-Law 56/2023 rule that real estate no longer qualifies — signaling the info's currency and limits.

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 English sentence is dense, front-loaded, and earns every clause. The trailing Portuguese restatement is largely redundant for an agent, which keeps this just short of 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, the description needn't explain return values, and it does fully characterize the guide's coverage plus the one optional language param. Only the lack of routing guidance relative to siblings keeps it from a 5.

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 the single 'idioma' enum (en/pt) is documented in the schema, so the baseline is 3. The bilingual phrasing hints at language support but adds no semantics beyond what the schema already provides (e.g., default behavior).

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 specific verb+resource ('Step-by-step guide for foreigners buying property in Portugal') and enumerates the exact topics covered: NIF, bank account, CPCV, taxes, deed, Golden Visa. An agent can distinguish it from calcular_custos_compra or pesquisar_imoveis without opening any schema.

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 — an agent can infer this is the process/overview tool versus the cost or listing siblings, but the description never states when to choose it over calcular_custos_compra or falar_com_consultor, nor any prerequisites.

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