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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds real behavioral content beyond that: results are sorted longest-first and the comparison includes holiday extensions and fees, telling the agent what data will be present. It doesn't mention result size, pagination, or whether all retailers are always returned.

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 short sentences with the substantive content (what is compared, sort order, included fields) front-loaded. The second sentence is mildly promotional ("no single shop's help page can") rather than informational, which is the only waste.

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 zero-parameter read-only comparison tool with no output schema, the description covers the essentials: scope (all retailers), ordering, and the fields included (holiday extensions, fees). Missing only edge details like coverage breadth or result format, which are minor at this complexity.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate and the baseline of 4 applies. The schema coverage is 100% and additionalProperties is false, so there is no hidden input surface.

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 the specific resource (every retailer's return window) and the operation (put side by side, sorted longest first), which an agent can distinguish from get_policy (single policy) and list_companies. It stops short of naming the sibling tools explicitly, so differentiation is inferred from the cross-retailer comparison framing.

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?

"Answers questions no single shop's help page can" implies this is the cross-retailer comparison tool and that get_policy covers the single-shop case, but the routing is left implicit. There is no explicit when-to-use, when-not-to-use, or named alternative.

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