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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), and the description adds substantial context beyond them: the data source (Portal da Transparência/CGU), no completeness or currency guarantee, scope limits, no legal advice, no personal data, filial consulting matriz, and the error contract (source error in `fontes`, `dados` null, never an empty list).

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 purpose, then a labeled usage clause, then source/limitations, then parameter behavior. Every sentence carries information (limitations, scoping, error contract), though the density is high and a couple of clauses could be trimmed without loss.

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 two-parameter lookup with an output schema, the description is complete: source, coverage boundaries, parameter semantics, ceiling behavior, and failure-mode shape are all covered, leaving no ambiguity about what the tool returns or fails to cover.

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 semantics beyond the schema: `limite` selects the most recent by data de assinatura among all found (up to 150 per CNPJ), and it explains the related return signals `total_encontrado` and `possivelmente_mais: true` as the read-ceiling indicator.

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: returns a Brazilian company's contracts with the federal executive, keyed by CNPJ. It also explicitly names the sibling that gives the broader view (relatorio_completo), so an agent can route between the two without opening schemas.

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?

Includes an explicit 'Quando usar' clause tied to a concrete need (supply history to the federal government with órgão, objeto, datas, valores) and names the alternative for the full picture. It further states when NOT to rely on the result: absence of contracts only means absence in the federal executive, not for states/municipalities or other branches.

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