SELIC Target (COPOM)

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

Annotations already declare readOnlyHint and idempotentHint, establishing the tool as safe and idempotent. The description adds some behavioral context (e.g., 'policy decisions') but does not disclose update frequency, rate limits, or other traits. The annotations carry most of the burden, making a score of 3 appropriate.

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 concise sentence that front-loads the key information (COPOM, SELIC target, series number). It includes licensing info but remains efficient. There is no wasted verbiage.

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?

Given the presence of an output schema (not shown) and comprehensive annotations, the description is minimally adequate. However, it lacks details about data frequency, update schedule (e.g., is it updated at each COPOM meeting?), or how the parameter behaves for this series. More context would improve usability.

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?

The input schema has 100% coverage with a description for 'last_n', but that description misleadingly references IPCA (a monthly series) which is irrelevant for SELIC target (set at COPOM meetings). The tool description provides no additional parameter clarification, missing an opportunity to correct the schema's inaccuracy or explain the parameter's behavior for this specific tool.

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 identifies the tool as providing the COPOM-set SELIC target rate (series 4389) from the Brazilian central bank. It gives a specific verb+resource and mentions the series number, making the purpose clear. However, it does not explicitly distinguish itself from the sibling tool 'finance.bcb.selic', which likely provides the actual SELIC rate, leaving some ambiguity.

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 offers no guidance on when to use this tool versus alternatives like 'finance.bcb.selic' or other BCB series. There is no mention of context, prerequisites, or exclusions, leaving the agent without direction on appropriate use cases.

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