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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. With no output schema, the description usefully carries the return-shape burden by spelling out what comes back (dimensions, attributes, per-option SKU/price/stock) and that only public data is exposed.

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 sentences, zero filler, and the payload scope is front-loaded before the identifier rule. 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 two-param read tool with full schema coverage and annotations, the description covers the return payload and the identifier constraint adequately. It stops short of stating behavior for an unknown SKU or an ambiguous/mismatched sku+url pair, which is the remaining gap.

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% so the baseline is 3, and the description earns above that by supplying the mutual-exclusivity constraint (exactly one of sku or url) that the flat schema with zero required fields cannot express. It also notes pricing is stated before VAT, a nuance absent from the schema.

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?

Names a specific verb+resource (get one product) and enumerates the payload: dimensions, attributes, and each option/variation with SKU, price before VAT and stock. That granularity distinguishes it from list-style siblings like search_products, though no sibling is named explicitly.

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 description gives a hard selection rule for the two identifiers ("Give exactly one of sku or url") and ties url provenance to search_products, but it never states when to reach for this tool instead of search_products or calculate_materials — the lookup-then-detail flow is only implied.

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