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

Annotations already cover readOnly/idempotent/non-destructive/closed-world, and the description adds substantial context beyond them: no API key required, rate limits (1000/hour and 10000/day per address, or the key's own limit with `chave_api`), that the values are historical and not a recommendation, and that a disclaimer note is included in the response.

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?

Front-loads the core promise and the parameter semantics follow logically, with no filler sentences. It is somewhat dense and the 'ABERTA' sentence restates the no-key condition awkwardly inside parentheses, costing a little readability.

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?

No output schema exists, so the description must convey the return shape — it does: ranking, name, DATA-BASE, criteria description, ticker/value rows, source and canonical source_url. Combined with the disclosed rate limits and auth model, an agent has everything needed to call it and interpret the result.

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?

Schema description coverage is 0%, so the description must carry the load — and it does. It enumerates every `lista` value with its meaning ('dividendos', 'pl', 'fiis') plus the empty-string default behaviour, and gives the `limite` range (1–20) and default (20), and explains the role of `chave_api` in the rate-limit context.

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 concretely what it returns: a pre-computed ranking with name, base date, criteria, ticker rows, source and source_url. It distinguishes itself from the alternative workflow of reading one page per stock to assemble a ranking, but never names the sibling ranking tools (dividendos, fiis_ranking, screener, etfs_ranking), so sibling differentiation rests on inference.

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?

Gives a clear directive: 'use esta ferramenta em vez de ler uma página por ação para montar um ranking', and explains that an empty `lista` returns a catalogue of all three lists. It lacks explicit when-not guidance and does not contrast with the closely related ranking/screener siblings.

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