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

Annotations already convey that the tool is read-only, idempotent, and non-destructive. The description adds useful runtime context beyond that: raw administrative API records, the default and maximum 'limite' values, the no-filter error, and the next-step tool. It does not clarify how 'numero' and 'objeto' interact when both are supplied, but the main behavior is well disclosed.

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 three compact sentences that front-load the purpose and then cover return shape, limits, error behavior, and a routing hint. Every sentence adds distinct value with no redundant or filler content.

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 search tool with three optional-looking schema parameters, the description covers all invocation-critical details: accepted filters, mandatory-filter rule, result limits, return structure, and the related contract tool. The output schema and annotations supply the remaining detail, so an agent has everything needed to call it correctly.

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 coverage is 100%, so the baseline is 3. The description adds the important cross-parameter constraint that at least one filter is mandatory despite the schema listing zero required fields, plus an example for 'numero' and the default/maximum for 'limite', which goes beyond the schema.

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 the action ('Busca'), the resource ('licitações do Senado'), and the two search modes: exact 'numero' or 'objeto' text. It also distinguishes itself from the contract-lookup sibling by pointing to senado_contratos, so an agent can tell what this tool is for without opening the schema.

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?

Explicit usage conditions are provided: at least 'numero' or 'objeto' is required, and omitting both causes an error. It also tells the agent to use senado_contratos for the contract resulting from a licitação, which is a clear when-not-to-use rule.

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