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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds the meaningful auth prerequisite ('Needs the user's Cotlet API key with access to this app') but offers nothing on rate limits, result freshness, or period-boundary behavior; with annotations doing the heavy lifting, this is adequate but thin.

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 metric list is duplicated verbatim – first in 'Per product: earnings, units sold...' and again in 'Returns the numbers of one product for a period: earnings, units sold...'. The redundant sentence and the echoed 'Teachers Pay Teachers:' prefix waste space, though the key instruction is reasonably front-loaded.

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 must describe returns, and it does enumerate the metric fields plus the auth requirement and the list_products dependency. For a simple three-parameter read tool this is nearly complete, lacking only period semantics or guidance on comparing against store-level stats.

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 product_id, from and to each documented in the schema, so the schema already carries parameter meaning. The description only loosely gestures at them via 'one product' and 'for a period'; it adds no format or constraint detail, matching the baseline 3 when the schema does the work.

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 and resource (get product stats) and enumerates the exact metrics returned (earnings, units sold, views, conversion, Wish Listed and Saved for Later), scoped to 'one product for a period'. The 'Per product' framing implicitly distinguishes it from the sibling get_store_stats, though it never names that alternative.

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?

Gives a concrete operating instruction: 'Call it for each product from list_products to rank them,' which tells the agent exactly how this tool fits into a workflow. It stops short of stating when to prefer this over get_store_stats or get_product, so no explicit exclusions are provided.

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