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

Beyond annotations (readOnly, idempotent, non-destructive), the description discloses critical behavioral details: settlement conventions ('lot settles D+1; sell uses Tesouro sell-back conventions'), a modeling limitation ('Coupons/installments between lot and sell are NOT tax-modeled'), and a warning condition ('IPCA_FORWARD_GAP_NOT_COMPOUNDED'). These give the agent far more than the annotation flags alone.

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 longer than typical, but it is front-loaded with the primary purpose and use cases, and every sentence adds needed detail (settlement, warnings, bulk, disclaimer). It is structured with clear logical sections, though a few sentences could be tightened without losing value.

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 complex tool with nested objects, many parameters, and an output schema, the description covers all necessary context: what it does, when to use it, parameter constraints, settlement behavior, tax-modeling gaps, future-date projection, bulk limits, and a disclaimer. Combined with the rich schema and annotations, an agent has everything needed to select and invoke it correctly.

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?

Though the schema has 100% coverage, the description adds essential cross-parameter logic: 'lot takes exactly one of price or rate', 'sell takes rate only', and the role of ipcaForwardMonthlyRate for future-dated sells. It explains how parameters relate and when to use them, which is value beyond individual field descriptions.

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: 'Simulates an early redemption' with a clear scope ('a historical acquisition lot and a hypothetical sell') and outputs ('gross sale pricing plus netReturns... annualized gross/net rates'). This unambiguously distinguishes it from siblings like simulate_bond.

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 strong 'USE THIS for' guidance with concrete Portuguese questions and scenarios ('quanto recebo líquido se vender?', IR/IOF/custódia, comparing gross vs net). It also notes bulk limits. It does not explicitly name alternative tools it should be preferred over, so it misses the 'alternatives' criterion for a 5.

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