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

Annotations already declare this as a read-only, idempotent, non-destructive, closed-world operation, so the safety profile is covered. The description adds meaningful behavioral context: it explains that the low-price comparison is against actual historical cost rather than a store's 'was' price, and it enumerates the returned components (today's lowest, recent range, low verdict). It does not specify how many days 'recent' covers or the data source granularity, but it goes beyond the annotations in useful ways.

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 description is a single, dense sentence that is front-loaded with the core purpose and then layers on the key semantic nuance (actual historical comparison vs. store 'was' price). Every clause earns its place, and there is no filler.

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 carries the burden of explaining return values, and it does so at a high level (today's lowest price, recent range, low-price verdict). It remains silent on the 'language' parameter, the exact lookback window, and any pagination or store coverage limits, which are minor but real gaps for a data-retrieval 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 50%: the 'product' parameter is well documented in the schema with an example, but 'language' has only an enum and no explanation. The description does not compensate by clarifying what 'language' controls or adding any parameter meaning beyond what the schema already provides.

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 clearly states the resource (daily price history) and scope (a specific product across stores), and lists the outputs (today's lowest price, recent range, low-price verdict). It does not explicitly differentiate itself from the sibling find_best_options, leaving the agent to infer that this is historical data rather than current option discovery.

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 phrases like 'price history' and 'whether today's price is low', suggesting a price-checking or deal-evaluation scenario. However, there is no explicit when-to-use/when-not-to-use guidance and no direct comparison to the sibling tool find_best_options.

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