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

Annotations already declare readOnlyHint and openWorldHint=false, yet the description still adds meaningful context: aggregate figures only with no creators named (privacy/aggregation behavior), no authentication required, and that the optional day returns an earlier snapshot. Missing only edge-case behavior (invalid date, days with no data).

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?

One dense sentence that leads with the resource and packs the return payload efficiently, with operational notes (optional day, no key) at the end. The run-on construction slightly impedes scanning but no sentence is wasted.

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 usefully enumerates the metrics returned, and the sole parameter is covered, so an agent has enough to call it. Only gap is failure/empty-result behavior for an out-of-range or data-less day.

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% and already documents the single optional day parameter including its format and 'latest day when omitted' default. The description's 'returns an earlier day' restates rather than extends that meaning, so the 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 concrete resource (the brand/shopping platform of the day on Instagram in Turkey) and enumerates the report contents, so an agent can distinguish it from the influencer-focused siblings without opening the schema.

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 conveys context (daily aggregate report, 'no key needed') and the day-override behavior, but never names an alternative or a when-not-to-use condition against siblings like trend_cloud or ai_search_influencers. Usage must be inferred from scope alone.

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