get_cdi

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It does state that the value is the most recent daily CDI in percent per day, which is useful, but it does not describe the return shape (e.g., single number vs. object with date) or any update/source behavior, leaving some ambiguity.

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 two short sentences with no filler. The key information—what the CDI value is, its frequency, and its unit—is front-loaded, and every clause contributes meaning.

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 parameterless, simple lookup tool, the description is nearly complete: it tells the agent what data is returned, the frequency, the unit, and the general use context. It lacks an explicit statement of return type, but with no output schema and such a simple resource, that omission is minor.

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 tool has zero parameters and the schema is empty, so there are no parameter semantics to clarify. With 0 params, the description is not required to add parameter detail; it still provides useful semantic context about the returned rate and its unit.

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 resource (CDI), the cadence (daily), the recency (most recent), the unit (% per day), and its role as a post-fixed income benchmark. It is far more specific than a tautology and distinguishes the tool from siblings like get_selic or get_ipca, though it does not explicitly name an alternative.

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 phrase 'Referência de renda fixa pós-fixada' implies when this tool is relevant, giving some usage context. However, there is no explicit guidance about when to use this tool versus alternatives such as get_selic or get_serie_sgs, so the agent must infer the appropriate selection.

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