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

Annotations already cover safety (read-only, idempotent, non-destructive, closed-world), and the description adds substantial context beyond them: data provenance (CVM monthly report + COTAHIST), a data-quality filter ('só valores limpos (sem flag) e fundos líquidos'), explicit rate limits with and without an API key, and the presence of a `citacao` field.

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 and every sentence carries information, but the phrasing is cluttered: 'ABERTA, sem chave (sem chave: ...)' repeats the same idea and the parenthetical rate-limit block interrupts the flow. Tightening could cut it meaningfully without losing content.

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 does the work of telling the agent what comes back (rankings, segment medians, `citacao`), plus provenance, filtering rules, and limits — enough to call it correctly. It could go slightly further on result shape/ordering, but nothing essential is missing.

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 single parameter `chave_api` has 0% schema coverage, so the description carries the burden — and it does explain the practical meaning (without a key: 1000/hour and 10000/day per address; with `chave_api` the key's own limit applies). It doesn't describe the key format or where to obtain it, so it is not fully complete.

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 resource (FIIs) and exactly what the ranking contains: lowest P/VP, highest DY 12m, and median P/VP and DY by segment. It also names the sibling it is not (screener_fiis), so an agent can distinguish the two without opening either 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?

Explicitly contrasts with screener_fiis ('O filtro em massa por faixas é `screener_fiis`, que exige chave'), giving a clear condition for choosing the alternative. It also states the tool is open/anonymous, which is a strong usage cue. It stops short of enumerating when-not-to-use cases beyond that one sibling.

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