SELIC Daily Rate

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

Annotations (readOnlyHint=true, destructiveHint=false, idempotentHint=true) already cover the safety profile. The description adds that it returns 'last N observations' and mentions the data source (BCB SGS) and license (ODbL), which provides useful context but does not reveal critical behavioral traits beyond annotations.

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 a single sentence with no redundant words. It is front-loaded with the core purpose and includes key details (series 11, source, license). Every word contributes value.

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 simple tool with one parameter, comprehensive annotations, and an output schema, the description is fully adequate. It specifies the exact series, source, and parameter behavior, leaving no gaps for an agent to misinterpret.

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?

Input schema has 100% coverage for parameter 'last_n' with a clear description including default and max. The description does not add extra semantic information beyond the schema, so baseline score of 3 is appropriate.

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 it returns the Brazilian SELIC daily interest rate (series 11) from BCB SGS, specifying the verb 'return', the resource 'SELIC daily interest rate', and the scope 'last N observations'. This distinguishes it from sibling tools like finance.bcb.cdi (CDI rate) and finance.bcb.ipca (IPCA inflation).

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 implies usage for SELIC daily rate queries but does not explicitly state when to use this tool versus alternatives or provide exclusion criteria. Sibling tools include other BCB rates, so the context helps, but no direct guidance is given.

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