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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new behavior: results are a bounded shortlist in catalog order rather than a ranking, there is no live inventory or checkout, and unknown regional software support does not satisfy required software features. That last rule is important negative semantics an agent could not infer from annotations.

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?

Four short sentences, each carrying a distinct constraint, with the core purpose front-loaded before the disclaimers. The telegraphic style ('No live inventory or checkout') is efficient, though the phrasing is clipped enough that a little more connective language could aid comprehension without bloat.

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 seven-parameter read-only search tool with no output schema, the description covers result shape (bounded shortlist, catalog order), the missing checkout/inventory capability, and one subtle matching rule. It still omits how limit, query, category and language affect results, so an agent knows the gist but not the full filtering contract.

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 only 43% across seven parameters, so the description must compensate. It clarifies the intent of country, use_case and required_features, including the non-obvious rule about unknown regional software support, but says nothing about limit, query, category or language, leaving several parameters documented only by terse schema fields.

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 opens with a specific verb and resource: 'Find source-checked smart glasses by country, use case and required features.' That tells an agent exactly what the tool retrieves and the primary filter dimensions. It does not name the sibling tools (compare_smart_glasses, get_buying_links), so the differentiation is implied by 'find' rather than stated.

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?

It gives useful boundary conditions — 'Returns a bounded shortlist in catalog order, not a best-product ranking' and 'No live inventory or checkout' — which tell the agent what this tool will and will not deliver. However, it never says when to choose this over compare_smart_glasses or get_buying_links, so routing between siblings is left to inference.

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