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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds meaningful behavior beyond that: the default comparison is the immediately preceding period of equal length, results are expressed as absolute and % deltas at both total and marketplace level. No output schema exists, but the metric list partly compensates by indicating what comes back.

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 sentences, front-loaded with the core behavior, then the usage examples. No filler, though the long first sentence packs metric list and default-window logic together, making it slightly dense to scan.

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 read-only, idempotent, zero-required-parameter comparison tool with a fully documented schema, the description covers default behavior, customizable baseline, metric set and breakdown granularity. Only the concrete response shape and any limits on period length are left implicit.

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 schema already documents each parameter and the baseline is 3. The description adds value the schema cannot: the implied default comparison window when compare_* dates are omitted, which is a semantic an agent would otherwise have to guess.

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 (compare) and resource (one period vs another) and enumerates the metrics returned (commission, sales, orders, clicks, conversion, EPC) with absolute and percentage variation per marketplace. It is clear enough to separate from plain breakdown tools, though it never names the closest sibling (painel_compare_marketplaces) or explains how it differs.

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?

Provides concrete invocation patterns ("this week vs last week", "October vs September") and explicitly tells the agent to pass compare_start_date/compare_end_date for a custom baseline. It does not state when to prefer an alternative such as painel_get_monthly_growth or painel_compare_marketplaces, so the routing guidance stops short of the top score.

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