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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive, so the safety profile is covered. The description adds meaningful context beyond that: results are limited to 'human scan' counts, codes must be 'owned', and the output is aggregate only, so conversion rates cannot be derived.

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 with the core purpose front-loaded and no filler. The second sentence is advisory rather than operational, but it is short and useful.

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 would ideally hint at the return shape (per-code counts vs. ranked comparison) and clarify the from/to/days parameter relationship. It covers purpose and a key caveat but leaves the mechanics of the time window underspecified.

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 0% across four parameters (ids, from, to, days), so the description carries the burden but only partially compensates. It conveys the 2-10 constraint on ids (already in schema min/maxItems) but says nothing about how days interacts with from/to, what format ids take, or that the period must be identical across all compared codes.

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 states a specific verb (compare) and resource (aggregate human scan counts) with an explicit scope: 2 to 10 owned QR codes over the same period. This distinguishes it from sibling get_analytics (single-resource analytics) without naming that sibling 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?

'Do not infer conversion rates without separate conversion data' is a caution about interpreting results, not guidance on when to choose this tool over get_analytics or get_qr_code. Usage is implied by the comparison framing but no alternatives or exclusions are stated.

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