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

Annotations already declare readOnly, idempotent, non-destructive, closed-world access, so the safety profile is covered. The description adds genuinely useful behavior beyond that: the search window adapts to the indicator's periodicity to absorb publication lag for annual series, and it explains the meaning of dataStatus = 'defasado'.

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?

Three compact sentences, front-loaded with the return content before the operational caveats (adaptive window, dataStatus). No filler, though the last sentence on dataStatus could sit more tightly with the window explanation.

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?

With no output schema, the description carries the return-value burden and does so well by naming every returned field plus the dataStatus qualifier. Slightly short only on edge behavior (unknown code, what happens when no prior value exists for the difference).

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?

Only one parameter and schema description coverage is 100% (the code field already documents itself with an example). The description adds nothing about code format, case sensitivity, or valid values, so the baseline 3 applies — the schema does the work.

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 a specific verb and resource ('Devolve o último valor disponível de um indicador') and enumerates the payload: último valor, valor anterior, diferença, período, unidade e fonte. This clearly separates it from get_indicator_series (full history) and get_indicator_details, though it never names those siblings explicitly.

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?

Usage is only implied by the wording 'último valor' — an agent can infer this is the right call when it wants the current reading rather than the time series, but there is no explicit when-to-use, when-not, or named alternative. It doesn't say what to do if the code is unknown or if a longer history is needed.

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