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

Annotations already declare readOnly/idempotent/non-destructive behavior; the description adds meaningful context: per-query prepaid charges, no platform credentials, official non-confidential data, and LGPD controller responsibilities. No contradiction with annotations, but it does not explain how 'senha' is used or what the response contains.

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 compact, front-loaded with the main action, and includes relevant payment/legal context. The LGPD clause adds some boilerplate, but overall the structure is efficient and readable.

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?

Despite strong annotations and some high-level context, the tool has five undocumented parameters and no output schema. The description omits how to supply identifying information or what the downloaded/consulted result looks like, leaving a significant invocation gap.

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 does not explain CPF, CNPJ, email, senha, or numero_instalacao. With five parameters and no schema-level descriptions, the description fully fails to compensate for the missing parameter semantics.

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 opens with 'Cemig: Download de Contas, consulta em fonte oficial', clearly identifying the resource (Cemig bills) and the action (download/consult). It is distinguishable from the sibling tools, though 'contas' could be read as 'accounts' rather than 'bills', so it stops short of full clarity.

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 gives useful context: use this tool to query official Brazilian Cemig data, using prepaid credit and without platform credentials. It does not explicitly state when not to use it or name alternative query tools, but the provided context is clear enough for selection.

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