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

Annotations already declare read-only/idempotent safety, so the bar is low, but the description still adds real behavioral detail: the reading cadence (hourly vs daily), the approximate lookback (~48 readings), the point encoding '[UTC time, value]', and critically that a gap means missing data rather than zero. That last note prevents a common misinterpretation and is exactly the kind of context structured fields cannot convey.

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?

Three tight sentences, front-loaded with what is returned, then when to use it, then how to read the payload. Every clause carries information: series types, cadence, use case, and the gap-vs-zero caveat; nothing is padding.

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?

Although an output schema exists, the description still supplies the two things an agent needs to interpret it correctly: sampling granularity and the gap semantics. Combined with complete parameter docs and non-destructive annotations, nothing material is missing for a read-only history tool.

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 the game, platform enum, and maxPoints bounds are already fully documented, which sets the baseline at 3. The description mentions '~48 readings' and 'most recent kept' implicitly but adds no format or fallback detail beyond the schema, so it neither compensates for nor undercuts the schema.

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?

Names the concrete resource (one game) and the exact series returned: hourly players online, daily positive/negative Steam reviews, cumulative visits/followers/reviews, and Wikipedia page views. The opening 'Time series' framing contrasts implicitly with the point-in-time sibling get_game, so an agent can distinguish them without opening 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?

'Use it to tell a lasting rise from a one-day spike' gives a clear positive trigger for when this tool is the right choice. It stops short of naming an alternative (e.g. get_game for a current snapshot) or stating when not to use it, so it is clear context but not full routing guidance.

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