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

Goes well beyond the readOnly/idempotent annotations by disclosing critical guardrails: never invent professional fee percentages, professional fees only from written quotes, do not produce a generic 'typical all-in' range, and never apply announced_not_in_force rates as current law. It also flags 'not legal or tax advice' and requires preserving the calculator link and assumptions.

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-loads the usage trigger and keeps everything in a single efficient paragraph, but repeats the 'professional fees only from amounts the user gives' rule twice, which is redundant emphasis rather than new information.

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, return values need not be described, and the description covers the computation, its guardrails, assumptions to preserve, and the announced-vs-in-force rate rule. Coverage is strong, though the meaning of registered_in_cadastre and the language enum is left to the schema.

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 coverage is 60%, and the description adds real meaning beyond the schema: tax is due on the higher of price vs objective value (objective_value_eur) and professional_quotes_eur must come from written, VAT-inclusive quotes. It does not explain the language enum or registered_in_cadastre semantics, leaving a small gap.

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 and resource ('estimate buying costs ... on top of the price to buy a resale property in Greece') and enumerates the components computed (transfer tax, municipal surcharge, Cadastre registration, notary's scale fee). This clearly distinguishes it from the sibling search/research tools.

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?

Gives an explicit trigger ('use this when the user asks how much it costs on top of the price to buy a resale property in Greece') and a clear boundary that professional fees enter only from user-supplied amounts. It does not explicitly name or rule out sibling tools, but the usage condition is unambiguous.

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