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

With no annotations, the description carries the full burden and does disclose core behavior: it simulates fixed income returns, calculates regressive income tax, and compares against poupança. However, it omits assumptions, output format, limitations, and the fact that LCA is not actually supported by the schema enum.

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 compact, front-loaded with the tool's purpose, and contains no filler. The instruction to use exact English parameter names earns its place, though the unsupported LCA mention slightly reduces accuracy.

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?

There is no output schema or annotations, so the agent needs more context about return values, assumptions, and how the result is presented. The description also fails to route the agent away from overlapping sibling tools and leaves a misleading LCA claim unresolved.

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 100%, so the schema already documents all parameters well. The description reinforces that the four parameters are mandatory and should be used with exact English names, which is mildly useful, but it adds no deeper semantics and does not resolve the LCA/enum mismatch.

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 uses a specific verb ('Simula rendimento de renda fixa no Brasil'), enumerates the investment types, and adds behavior details like IR regressivo and comparison with poupança. However, it does not explicitly differentiate this tool from overlapping siblings such as calculate_lci_lca, calculate_tesouro_selic, or compare_investments, and it mentions LCA even though the schema enum does not include it.

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 description provides no guidance on when to use this tool versus alternatives like calculate_lci_lca, calculate_tesouro_selic, compare_with_cdb, or compare_investments. The only instruction given is about using exact parameter names, which is parameter guidance rather than tool-selection guidance.

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