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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description goes beyond that by disclosing what is returned: the official description from the current table plus a link to a page of example products — meaningful output context given there is no output schema. It stops short of saying what happens for an invalid or retired code.

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?

A single well-formed sentence that front-loads the primary output (the official description) and appends the secondary return (example-products link). No filler, no repetition of the schema.

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 one-parameter, read-only lookup with no output schema, the description is nearly self-sufficient: it names the source table, the identifier format, and the two things returned. The only gap is behavior on unknown/invalid codes, which is minor for this tool shape.

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 there is exactly one parameter whose format (8 digits, with or without dots) is fully documented in the schema. The description's 'NCM (Nomenclatura Comum do Mercosul, 8 dígitos)' only expands the acronym, adding no syntactic detail beyond the schema, so the baseline of 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 (devolve) and resource (descrição oficial de um código NCM de 8 dígitos) plus the scope of the source table ('tabela vigente'), so the agent knows exactly what lookup is performed. It does not name or contrast the siblings buscar_produtos or consultar_codigo_barras, so the tool is clear in isolation but not explicitly differentiated.

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 described input contract (an 8-digit NCM code) and the returned content, which makes the intended scenario inferable. However, there is no explicit when-to-use statement, no exclusion, and no pointer to buscar_produtos for product-level queries or consultar_codigo_barras for barcodes.

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