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

Annotations already declare readOnly, idempotent, non-destructive behavior, so the safety burden is covered. The description adds real behavioral context beyond that: results are market-specific (prices, titles and links follow the market) and it lists cross-sell data (other in-stock colours/sizes with URLs) that an agent would not otherwise expect.

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?

Front-loaded with the core purpose and identifier, then a dense field list in a single sentence. It is appropriately sized for the amount of return information conveyed, though the long enumerated tail reads as a dump rather than structured guidance.

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?

With no output schema, the description carries the return-value burden and does so by enumerating price, availability, brand, dimensions, weight, volume, material, colour, image, variant URLs and airline fit. Combined with the market-scoping note and URL formats, an agent has everything needed to call it correctly.

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 parameters documented, including the ee/lv enum and default. The description still adds syntax not present in the schema by giving concrete URL path shapes (kohvrimaailm.ee/toode/..., koferuveikals.lv/prece/...), helping the agent recognize a valid handle_or_url value.

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+resource ('Full facts for one product') and enumerates the returned dimensions, which lets an agent distinguish it from search_products. However, it claims to return 'which airlines' personal-item or cabin limits it fits', which overlaps with the check_airline_fit sibling and is not differentiated.

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 only implied: the schema note that the handle comes 'from search_products' sketches a search-then-fetch flow, and the URL forms hint at direct linking. There is no explicit statement of when to prefer this over search_products, check_airline_fit, or recommend_for_trip, and no exclusions.

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