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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely useful behavioral context beyond that: the depreciation projection is explicitly flagged as a statistical estimate from Carpedia, not official FIPE data, which protects the agent from presenting it as authoritative.

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?

A single front-loaded sentence with no filler; the parenthetical caveat is the one extra clause, and it earns its place by disclosing data provenance. Dense but not bloated.

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 two-parameter, read-only history tool with no output schema, the description covers the essentials: what series is returned, that variation and a depreciation projection are included, and the caveat on the projection. Return-format details (granularity, pagination) are not addressed, which is a minor gap.

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 'ano' format and the fipeId meaning are fully documented in the schema. The description restates the 'versão×ano-modelo' pairing but adds no format, edge-case, or syntax detail beyond what the schema already provides; baseline 3 is appropriate.

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 verb+resource: the historical FIPE price series for a version×model-year, plus variation and depreciation projection. The 'série histórica' framing naturally distinguishes it from the sibling carpedia_preco_fipe (current price), but the description never names that sibling, so routing is left partially to inference.

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?

Usage is implied by the subject matter (an agent would infer 'use this when you need price history over time'), but there is no explicit when-to-use, no when-not-to, and no named alternative such as carpedia_preco_fipe for a snapshot price.

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