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

Annotations already establish the safe-read profile (readOnlyHint=true, destructiveHint=false, openWorldHint=false). The description adds genuinely new behavioral context: readings are periodic dated snapshots (often weekly) rather than daily tracking, and the dual series is explained as the way to tell a real drop from a cheaper seller appearing. It stops short of describing pagination or result shape.

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 tight sentences, front-loaded with what is returned and followed by the caveat that changes how the data should be read. Every clause carries information; nothing is redundant with the title or annotations.

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 must carry the return-value burden, and it does explain the two series and the snapshot cadence. Minor gaps remain (no mention of ordering, result shape, or behavior when the product has no history), but an agent has enough to call it correctly.

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% with only two parameters, both already documented (product id/slug, days window with default 180 and bounds). The description reinforces the single-product scope but adds no syntax, default, or format detail beyond the schema, 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?

The description gives a specific resource and scope: 'Recorded price history of one product', and clarifies the two data series returned (best price per day and per-offer series). It distinguishes the tool from a current-deals tool by emphasizing recorded history, though it never names the siblings get_deals/get_product/search_products explicitly.

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 implied by the purpose statement – an agent can infer it is the tool for retrieving a single product's price timeline – but there is no explicit when-to-use, when-not-to-use, or routing against the sibling tools. The snapshot-cadence note adds interpretive context but is not a usage rule.

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