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

Annotations already declare readOnly/idempotent/non-destructive behavior, and the description adds meaningful context: the list is raw upstream data, may include historical records like deceased senators, may have inconsistencies with parliamentary details, and does not include titular↔suplente linkage. This goes beyond the annotations and does not contradict them.

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 dense but efficient: purpose, return shape, parameter requirement, caveats, and routing are each covered in compact sentences. Every clause adds value and nothing is redundant.

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 zero-parameter, read-only list tool with an output schema, the description covers everything needed: result structure, data-quality caveats, and explicit alternatives. An agent can confidently select and invoke this tool without additional context.

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?

There are zero parameters and the description explicitly states 'Não requer parâmetros.' Since the input schema already documents this with an empty properties object, the baseline of 4 applies; there is no parameter detail left to explain.

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 uses a specific verb ('Lista') and resource ('senadores atualmente afastados'), making the tool's purpose immediately clear. It also distinguishes itself from siblings by explicitly pointing to `senado_listar_senadores` for active senators and `senado_obter_senador` for detail.

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 explicit routing: use this tool for afastados, `senado_listar_senadores` for em exercício/name search, and `senado_obter_senador` for detail and mandatos to identify substitutes. It also warns about the raw upstream scope and lack of legislature filtering.

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