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

No annotations exist, so the description carries the full burden. It does add a real behavioral fact the schema cannot express — the $0.002 per-call price — but says nothing about failure behavior for unknown codes, whether either identifier alone suffices, or rate limits. The cost disclosure is the only meaningful addition.

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?

One compact sentence plus a two-word input instruction and a price note. Front-loaded with the resource and return values; nothing 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 2-param lookup with no output schema, the description usefully names the return fields, compensating for the missing output schema, and discloses cost. The remaining gap is that it never clarifies that at least one identifier is effectively required despite required_parameters being 0.

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 both parameters (COMPE code format, ISPB 8-digit format) are already documented. The description adds that both are registry-keyed identifiers and that either can be supplied, but it does not resolve whether both may be passed together or which wins. Baseline 3 applies.

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?

States the resource (Brazilian bank), both accepted identifiers (COMPE code, ISPB), the authority (Central Bank registry), and the returned fields (short and full legal name). An agent can identify this as the bank-code lookup without opening the schema, and it is distinct from lookup_cep or validate_identifier.

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?

'Provide code or ispb' tells the agent which inputs to supply, which is implied usage guidance, but there is no statement of when to prefer COMPE vs ISPB, no error/not-found handling, and no named alternative. Adequate but thin.

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