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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the safe read nature is known. The description adds that it returns the invoices and a summary with quantity and total value, which is useful context about the return structure.

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?

The description is concise (two sentences) and front-loaded with the core purpose. However, it is compact and could afford a bit more detail without becoming verbose.

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 read-only query tool with no output schema, the description gives a basic understanding of the return (NFs + resumo), but it lacks details on parameter requirements, date format, pagination behavior, or how it differs from similar tools. Given the complexity of 6 parameters with 0% schema coverage, this is only minimally adequate.

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 0%, and the description only mentions 'por período' (by period) which relates to data_inicial/data_final, but it does not explain the meaning of loja, page, limit, account, or the date format. With 6 parameters, the description adds very little value beyond the schema types.

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 clearly states it returns purchase invoices ('notas fiscais de entrada do tipo Compra') for a store within a period, and mentions it includes a summary. It is distinct from siblings like cigam_vendas and cigam_notas_fiscais, though it doesn't explicitly differentiate itself.

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?

The description implies it is for querying purchase invoices by store and period, but it doesn't explicitly state when to use this tool over others like cigam_notas_fiscais or cigam_vendas. It also doesn't mention required parameters (loja) or that data_inicial/data_final are optional.

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