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

Annotations already cover read-only, idempotent, closed-world, and non-destructive behavior, so the bar is lower. The description still adds real context by specifying that only *public* details are returned and that a comparison page is produced, which tells the agent what to expect from the response beyond the safety profile.

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 front-loaded sentence that identifies the operation first and then the outputs. The colon-delimited list is efficient, though the phrasing 'each one's public details side by side, which has more community upvotes, and the comparison page' is slightly compressed and could read more cleanly.

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 two-parameter read tool with full schema coverage, complete annotations, and an output schema carrying return details, the description is nearly complete. The one omission is how the agent obtains slugs in the first place (e.g., via search_products), which matters in a catalog of listing tools.

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 coverage is 100%, with both `a` and `b` documented as product URL slugs, so the baseline is 3. The description's '(by their slugs)' restates the schema without adding format examples, slug derivation, or ordering semantics.

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 names a specific verb (compare) and resource (two products), and additionally enumerates what the comparison covers: side-by-side public details, upvote differential, and the comparison page. This is far more concrete than siblings like get_product, though it never names those siblings to sharpen the distinction.

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 the tool's nature: use it when you have two product slugs and want them contrasted. There is no explicit when-to-use vs. when-not guidance, and no pointer to alternatives such as get_product (single product) or get_alternatives (suggested substitutes), which an agent could easily confuse with this tool.

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