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

Annotations already cover safety (readOnlyHint=true, openWorldHint=false), so the bar is lower, and the description adds genuinely non-obvious behavior: readings are periodic snapshots (often weekly), not daily tracking, plus an instruction to quote dates and reading counts. This data-freshness caveat is exactly the kind of disclosure annotations cannot carry.

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 sentences, zero filler, with the returned data shape front-loaded and the snapshot caveat plus quoting instruction following. Every clause carries information an agent needs.

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 carries the burden of describing returns and does so adequately: best-price-per-day series plus per-offer series. Combined with the snapshot cadence and window parameter, an agent has enough to call the tool and interpret results 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% and both parameters (product, days with default 180 and 1-365 range) are documented in the schema itself. The description adds only the notion of 'readings' sparsity, which indirectly frames the days window, but specifies no format for the product identifier beyond what the schema says.

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 verb+resource ('recorded price history of one product') and clarifies the two granularities returned: best price per day across all offers and the per-offer series. It implicitly separates itself from get_product (current state) and get_deals, but never names a sibling to make the distinction explicit.

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?

Useful context is implied via the stated goal ('so you can tell a real price drop from a cheaper seller appearing'), which tells the agent this is the tool for price-trend questions. However, there is no explicit when-to-use/when-not guidance and no alternative tool is named or excluded.

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