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

No annotations, so the description carries the full behavioral burden. It usefully discloses a non-obvious return trait — output is filtered to differing specification fields only, not the full records — but says nothing about error behavior for out-of-range SKU counts, missing SKUs, or the shape of the comparison result.

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 sentence with zero filler, front-loading the operation before the output-filtering detail. Every clause earns its place.

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?

For a one-parameter comparison tool with no output schema, the description covers the essential operation and the key return behavior (differences only). It stops short of specifying the result layout or edge-case handling, but nothing critical to selecting or calling the tool is missing.

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?

Only one parameter, and schema description coverage is 100% with minItems/maxItems already encoding the 'two to four' rule. The description's 'two to four SKUs' merely restates the schema constraint, adding no semantics beyond it, 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 verb (compare), resource (SKUs/products), and scope (two to four side by side). The comparative framing plus the 'only fields where they differ' clause makes it unmistakably distinct from sibling read tools like get_product and search_products.

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?

The two-to-four SKU range and 'side by side' framing imply a comparison task, but there is no explicit when-to-use versus when-not, and no sibling (e.g. get_product for a single SKU) is named. Usage is inferable rather than guided.

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