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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds genuinely useful behavior beyond that: only clean values enter (P/VP and DY without flag), results are sorted by ascending P/VP, and there is a hard cap of 100 results, plus the auth requirement. It stops short of describing the response shape or pagination.

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?

Dense and front-loaded: the purpose, then the filter contract, then the data-quality rule, ordering, cap and auth, all in a handful of sentences. The example dict slightly overlaps with the subsequent key list, a minor redundancy, but no sentence is wasted.

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 read-only screener with no output schema, the description should ideally tell the agent what comes back. It discloses ordering (P/VP ascending) and the 100-item cap but not the returned fields or whether the result set is truncated silently. Filter semantics and auth are complete, so the gap is confined to the return contract.

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 coverage is 0% and 'filtros' is a free-form nested object with additionalProperties, so the description carries the full burden and does so well: it gives a concrete example dict and enumerates every valid key with semantics (pvp_min/max, dy_min/max inclusive bounds, segmento exact case-insensitive match, cotistas_min as a liquidity floor). It also documents chave_api as the required free-or-Pro key.

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 opens with a specific verb and resource: 'Filtra os FIIs por faixas' (filters FIIs by ranges), which tells an agent exactly what the tool returns. It does not explicitly differentiate itself from the sibling 'screener' (presumably the equity equivalent) or 'fiis_ranking', so the agent must infer the boundary from the 'FIIs' scope alone.

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 implied rather than stated: it is clearly the tool for range-filtering FIIs, and the auth prerequisite 'Requer chave_api (grátis ou Pro)' is disclosed. However, there is no guidance on when to prefer this over 'screener', 'fiis_ranking' or 'fii', and no exclusions or preconditions beyond the API key.

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