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

With no annotations provided, the description carries the full burden of behavioral disclosure. It adds useful context beyond basic ranking: data sources ('informe mensal da CVM + COTAHIST'), data filtering ('só valores limpos (sem flag) e fundos líquidos'), authentication requirement ('Requer chave_api'), and a note about free access to a specific ticker ('MXRF11 é aberto para degustação'). This gives the agent meaningful insight into how the tool behaves.

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?

The description is two sentences and front-loaded with the core purpose (ranking FIIs). Each clause adds distinct information: criteria, data sources, quality filters, and authentication. There is no redundant filler, though some domain abbreviations (P/VP, DY) may be less accessible to general audiences.

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?

Given the simplicity of the tool (one param, no output schema) and lack of annotations, the description provides a solid overview of what the tool returns (rankings and medians) and its data provenance. However, it omits practical details such as result limits, default sorting, output format, or whether all FIIs are included, leaving some ambiguities for the agent.

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 input schema only shows a parameter named 'chave_api' with no description (schema coverage 0%). The description compensates by explaining that this is an API key, mentions free and Pro tiers, and states it is required ('Requer chave_api'). This adds essential meaning beyond the raw schema definition.

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 clearly states the tool's function with a specific verb and resource: 'Ranking dos fundos imobiliários (FIIs)' and details the ranking criteria (most discounted by P/VP, highest yield by DY 12m, and medians per segment). It distinguishes itself from siblings like 'screener_fiis' by focusing on rankings and aggregate statistics rather than screening.

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?

The intended use is implied through the description (it provides rankings for FIIs), but there is no explicit guidance on when to choose this tool over alternatives like 'screener_fiis' or 'fii'. No exclusions or alternative recommendations are provided, though the context is clear enough for an agent to infer basic usage.

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