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

With no annotations, the description carries the behavioral disclosure burden and does well by explaining that 'historical' reads from data/tr_historical.json while 'projected' uses a constant base TR. It does not cover edge cases like default scenario behavior or failure modes, which keeps it from a 5.

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?

Two concise sentences with no filler. The main purpose is front-loaded, and the mode explanation is compressed into the second sentence without redundancy.

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?

The description is mostly adequate for a 3-parameter tool, but because scenario is optional in the schema and no default is documented, it is unclear what happens when scenario is omitted. There is also no output schema, so the description should ideally mention the returned series' format or structure; this gap leaves the definition incomplete.

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 100%, so the baseline is 3. The description adds meaningful semantic value by tying the scenario parameter to concrete behavior: historical mode uses the JSON file, projected mode uses the constant TR base, which clarifies the role of baseTR beyond the schema.

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 names a specific verb ('Retorna'), a specific resource ('série mensal projetada de TR'), and the domain context ('financiamentos indexados'). This clearly differentiates it from siblings like simulate_buy_vs_rent or calculate_cet.

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?

It provides clear context for when to use the tool — any need for a projected monthly TR series — and explains the two scenario modes. However, it does not explicitly mention alternative tools or state when not to use it, so it stops short of full routing guidance.

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