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

Annotations already mark readOnlyHint=true and destructiveHint=false, covering the safety profile. The description adds valuable behavior: the series is historical and explicitly not a projection ('não projeção'), limited to top N categories by volume, and includes mean/median/standard deviation and trend. This goes beyond the annotations and clarifies what the agent should expect.

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 dense, efficient sentences: the first defines the output and its constraints, the second provides usage and alternatives. No filler or repetition; the core concept is front-loaded.

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?

An output schema is present, so return values are already structurally documented. With no required parameters and all optional ones covered, the description provides purpose, scope, usage context, and alternative routing. Nothing essential for an agent to decide whether and how to invoke this tool is missing.

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 all three parameters already have descriptions including format (YYYY-MM or YYYY-MM-DD) for from/to and range plus default for top. The description adds only marginal semantic value by linking 'top' to 'top N categorias' and implying from/to define the analysis window. A baseline of 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?

The description opens by stating exactly what the tool returns: a monthly historical series (not a projection) broken down by category, limited to top N categories, with statistics and trend. It explicitly contrasts itself with analytics_history and categories_insights, so an agent can distinguish it from siblings without inspecting schemas.

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 gives an explicit use context: 'Use para sazonalidade/comparar categorias ao longo do tempo'. It then names two alternatives and the exact conditions for choosing them: analytics_history for the general total without category breakdown, and categories_insights for current vs previous month without a long series. This fully routes the agent.

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