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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds value beyond them by disclosing the data source (ITBI), the 12-month window, the historical depth (series since 2006), and the one-call-per-neighborhood cost model, which is useful for planning multi-neighborhood queries.

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?

Dense but front-loaded: the core answer (what price, where, over what window) leads, followed by returned metrics and then usage. Every clause carries information, though the metrics list is a long run-on that could be trimmed or bulleted for faster scanning.

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?

No output schema exists, so the description correctly takes responsibility for enumerating the returned fields, the data source, the time window and the historical series. Combined with a fully documented single parameter and complete annotations, an agent has everything needed to call this tool correctly.

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 100%, so the baseline is 3, but the description adds real meaning: the parameter accepts any of the 96 districts and also the city-level value 'São Paulo', which the schema only hints at with one example. This clarifies the input domain beyond the single schema description.

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 concrete verb+resource+scope: price paid per m² in a São Paulo neighborhood/district over the last 12 months from ITBI, with the metric set enumerated (median m², 12-month variation, apartment vs house, range, ranking position, series since 2006, top streets). The neighborhood-level granularity is clear, though it never names the sibling that covers a different granularity (vendas_rua, vendas_predio, ranking_bairros).

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 a concrete trigger example ('Use para "Pinheiros valorizou?"') and an invocation rule ('Uma chamada por bairro'), plus the accepted input surface (96 districts, neighborhood names, 'São Paulo' for the city). It stops short of explicit when-not-to-use conditions or naming alternatives among the nine siblings.

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