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

Beyond the annotations (readOnly/idempotent/destructive/openWorld), it discloses auth needs (keyless, chave_api optional), cost assumptions ('SEM custos', premissas returned), price-adjustment behavior and a past-measure disclaimer. That is substantive context; it does not, however, cover latency, limits, or data coverage edge cases.

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?

Purpose is front-loaded, but the body is a single dense paragraph riddled with nested parentheses, semicolons and capitalized emphasis, making it harder to scan than it needs to be. Nearly every clause carries information, yet the layout could be tightened without loss.

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 and 0% schema coverage, the description compensates by naming the return fields (retorno_total_pct, premissas) and the estimation assumptions. Enough is covered to call the tool correctly, though response structure and date formats are only loosely implied.

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?

With 0% schema description coverage, the description carries the load and largely does so: it fixes the default period (last 5 years), explains media_curta/media_longa via 'cruzamento de médias móveis (padrão 21 × 100)', and states that chave_api is accepted but unnecessary. It leaves the string format of de/ate unexplained.

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?

It names a specific verb and resource and enumerates the exact outputs computed (retorno, drawdown máximo com datas, volatilidade do comprar-e-manter, cruzamento de médias móveis). It also positions itself against a concrete alternative ('em vez de baixar a série diária'), so an agent can separate it from the price-series tool without opening the schema.

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?

It gives an explicit use-case trigger ("essa estratégia valeu a pena?") and steers away from the daily-series approach. The exclusion is stated behaviorally rather than by naming the sibling tool (precos), so it stops one step short of a fully named when/when-not statement.

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