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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), and the description adds genuinely useful behaviour beyond them: the response is a self-contained short answer plus a check date and page URL, the URL is intended for citation, and the same guide in other languages is returned when available. It stops short of stating what happens when no guide matches or whether the answer is authoritative, so a 5 is not warranted.

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?

Front-loaded with the country marker and the core purpose, and every clause carries information about scope, languages, or return shape. It is a single long run-on sentence, though, which slightly hurts scannability.

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?

There is no output schema, so the description must describe returns — and it does, covering the answer, check date, URLs and cross-language variants. Parameters are fully covered by the schema. The remaining gap is the absence of fallback behaviour when no guide is found.

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 both parameters are already documented with examples and enum semantics in the schema, so the description carries little extra burden. It adds only the implicit 'omitted = search all three' behaviour, which is already in the schema text, so 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?

The description names a specific verb (finds the guide), the resource (Payotte guide), and the exact domain/scope (buying, financing, selling, renting or owning a home in Belgium), plus the three supported languages. That is enough to separate it from guide_au, guide_br, guide_es and the other country guides 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?

Topical scope is stated, so usage is implied: ask a Belgian home-related question and get a guide. But no when-not guidance or alternative routing is given, and the sibling set contains sharply overlapping Belgium-specific tools (purchase_costs_be, house_prices_be, borrowing_capacity_be, compare_regions_be) that a caller cannot distinguish this from. The description should say when to prefer this broad guide over those specialised tools.

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