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

Beyond the readOnlyHint/idempotentHint annotations, the description adds meaningful behavioral details: the endpoint, the client-side nature of the `esfera` filter, the implication for `_total_registros`, and a 15-minute cache. These details help the agent understand data freshness and filtering semantics.

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 core function, and each sentence earns its place: purpose, endpoint, use cases, filter caveat, and cache. There is no redundant wording or filler.

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 listing tool with an output schema, the description covers all essential context: what it lists, why it is useful, the optional filter behavior, and data freshness. Required parameters are already documented in the schema, so nothing critical is missing.

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%, so the schema already documents every parameter, including the `esfera` client-side caveat. The description adds minimal parameter-specific meaning beyond that, which matches the baseline of 3 for fully covered schemas.

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 a specific verb and resource: 'Lista contratações com prazo de proposta aberto no PNCP', and identifies the exact endpoint. The phrase 'prazo de proposta aberto' clearly differentiates this tool from sibling listing tools such as compras_pncp_contratacoes_publicacao or compras_pncp_contratacoes_atualizacao.

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 use cases: mapping open opportunities for suppliers and identifying ongoing contracting in similar agencies. It does not name alternatives or state when not to use this tool, so it stops short of the top score, but the context is clear and actionable.

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