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

With annotations already covering readOnly/idempotent safety, the description goes well beyond them: it discloses the point structure (recorded_at, price, volume), that price is in cents and represents a median, the resolution policy (hourly for the recent month, daily beyond, one point per day for ranges of a year or more), how far back history reaches (2015), the empty-result condition, and the one-hour cache. This is exactly the behavioral context an agent needs before calling.

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?

The purpose is front-loaded in the first sentence, and the dense detail that follows is mostly load-bearing. Some of the granularity/caching detail could be tightened, and the mid-sentence line breaks make it slightly harder 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?

There is no output schema, so the description must carry the return shape, and it does: field names, units (cents), semantics of price and volume, and the granularity variations. Combined with the disclosed failure mode and cache behavior, an agent has everything needed to call and interpret the result.

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 baseline is 3, but the description adds real semantics the enum cannot: it explains that longer ranges change granularity and aggregation (median price, summed volume), which affects how the caller should interpret `range`. The itemdefid parameter gains no explanation beyond 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?

The title and first sentence state a specific verb+resource: Steam sale history for one skin, sourced from Steam Community Market's listing page. It is distinguishable from get_skin_price by the word 'history', but it never explicitly contrasts with that sibling or with get_item_store_history, leaving the agent to infer the boundary.

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?

Usage is only implied by the description of what the series contains. The one exclusion stated ('Empty when Steam has no sale series... unmarketable skins') concerns result emptiness, not when to choose this tool over get_skin_price or get_item_store_history. No explicit when-to-use guidance is given.

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