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

Annotations declare readOnlyHint, idempotentHint, destructiveHint=false, so safety is covered. The description adds the conditional behavior (all years vs single year + variation), which is useful, but doesn't explain the return shape beyond 'variação' or note any limits. Good added context, not rich.

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 clauses, front-loaded with the primary output, zero waste. The conditional behavior is stated compactly and clearly.

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 a simple read-only tool with full schema coverage and no output schema, the description covers the key behavioral branching. It lacks explicit differentiation from `carpedia_historico_preco` and `carpedia_resumo`, which would help an agent choose the right tool among many siblings.

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 both parameters are fully documented in the schema, including the special '32000' value. The description's mention of `ano` behavior is redundant with the schema, so baseline 3 applies.

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?

States a specific resource (FIPE price of a vehicle version) and the identifying key `fipeId`. Clear verb-less but precise noun+scope. It does not explicitly distinguish from sibling `carpedia_historico_preco`, which also deals with prices over time, leaving some ambiguity.

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?

Implies usage via parameter behavior (with/without `ano`), but gives no explicit when-to-use guidance or alternatives. An agent must infer that this is the current-price tool vs `carpedia_historico_preco` for past prices.

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