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

With no annotations, the description carries the full burden and does disclose meaningful traits: return shape (country series with timestamped points and a 'latest' value), no pagination, and that some requested countries may be unavailable. It omits any note on authorization or rate limits, but the operational caveats it does give are valuable.

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?

Front-loads what it returns and is dense with constraints, but the 'days does not define the aggregation period' caveat duplicates the schema description, so a small amount of redundancy is present.

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 is responsible for return semantics and does describe the country-series/timestamped-point/latest structure, plus the no-pagination constraint. Slightly more on how 'latest' relates to the window would make it fully complete.

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 all three parameters are already documented in the schema. The description's points about 'days selects the chart window, not the aggregation period' largely restate the schema wording, and the extra 'global is not a substitute for missing country data' is only marginally additive; 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 specific verb and resource ('fetch the source-reported time series for one CSI queryId') plus the scope of the date window and multi-country option. It is clearly distinguishable from sibling tools like search_topics (which supplies the queryId) and trending_topics.

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?

Gives clear context and explicit exclusions: do not label values monthly search volume, do not sum rolling values, use only returned countries and not global as a substitute. It does not, however, name an alternative tool or state when a different tool would be preferable.

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