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

Annotations already declare readOnlyHint/idempotentHint/non-destructive, so the safety profile is covered. The description adds genuinely useful behavior beyond that: it returns a short answer, a check date, and a URL, which matters since there is no output schema. It doesn't cover failure behavior or coverage limits, keeping it below a 5.

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?

One front-loaded sentence with the country marker "SPAIN." first. Efficient, though the long parenthetical (NIE, IRNR, 3% withholding, golden visa) is keyword-stuffed rather than strictly necessary.

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-parameter lookup with full schema coverage and annotations covering safety, the description supplies the missing return-shape info (short answer, check date, URL). An agent has enough to call it correctly; only routing guidance against overlapping siblings is absent.

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 parameter is already documented as "The question or keywords." The description contextualizes the kind of question expected but adds no syntax, format, or length guidance beyond the schema. Baseline 3 applies.

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 ("Finds") and resource (the Payotte guide) and scopes it to SPAIN, listing the covered topics (buying, financing, selling, renting, owning). It distinguishes itself from the parallel country guides, though it doesn't explicitly say why an agent should pick this over the more specific siblings like non_resident_tax_es or purchase_costs_es.

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 implied by the topic list (a question about buying/renting/owning a home in Spain), but there is no explicit when-to-use, when-not-to-use, or named alternative. It never tells the agent to prefer this broad guide versus the narrower Spanish tools that overlap in subject matter.

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