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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description contributes beyond that by disclosing the calculation itself (commission ÷ Meta spend) and the shape of the result: GMV in cents and derivatives in basis points — unit conventions an agent would otherwise have to guess, since there is no output schema.

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 compact sentences: the first front-loads the operation, formula, and granularity; the second adds output fields and a usage hint. No filler, though the final fragment is terse enough that its intent is only partly conveyed.

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?

With no output schema, the description correctly takes on the burden of enumerating returned metrics and their units. Date-window precedence is handled by the schema. What remains thin is guidance on when this is the right tool versus other analytics siblings, but nothing needed to invoke it correctly 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%: days range, level enum with default, and date formats are all documented in the schema. The description only restates that results are per level and per period, adding no format or precedence detail beyond what the schema already provides, 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?

The description states a specific verb and resource — computes ROAS (commission ÷ Meta spend) over a period, broken down by campaign/adset/ad — plus the metric set returned. It does not explicitly contrast itself with siblings like pixel_get_dashboard_summary or pixel_get_daily_trends, so differentiation is left 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?

The closing phrase "Base para escalar/pausar" implies a decision-making use case (scaling or pausing campaigns), which is helpful context. However, it gives no explicit when-to-use vs when-not guidance, no prerequisites, and does not name an alternative tool for a different level of aggregation or a summary view.

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