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

Annotations already establish readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful behavioral context beyond that: it discloses which data is aggregated (lowest retailer price over 30/90-day windows) and, importantly, that bundles and refurbs are 'marked and left out of the range' — a filtering behavior an agent could not infer from annotations.

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?

A single dense sentence, appropriately front-loaded with the resource before the detail clauses. Every clause carries information, though the long parenthetical listing return fields makes it slightly harder to parse than an explicitly split sentence would be.

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?

No output schema exists, so the description must carry return-shape information, and it does describe the returned data (first/last observation, range, the points themselves, bundle/refurb handling). Minor gaps remain — currency/units and whether the 30/90-day windows are relative to now — but the definition is largely complete for a simple read 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?

With a single parameter at 100% schema description coverage, the schema already documents product_slug with an example. The description adds nothing about slug format or sourcing beyond what the schema provides, 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 specific resource (dated price history for one product) with concrete scope: lowest retailer price in the last 30 and 90 days plus the full researched observation history. This clearly distinguishes it from siblings like get_product, compare_products, and get_release_history, which an agent can rule out 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?

There is no explicit when-to-use or when-not-to-use guidance. The description never mentions compare_products as the alternative for multi-product price comparison, nor does it state any precondition (e.g., that a slug from list_products/search is needed). Usage is only inferable from the resource name.

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