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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds real behavior: `current` marks the requested variant and is always listed, `family_id` names the group, `axes` explains differentiation, and prices reflect `deliver_to_country`. It also discloses the upstream endpoint it mirrors, aiding predictability.

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 resource, then the returned fields, then the usage instruction and the endpoint mirror. Dense but every clause carries information; the long field enumeration makes it slightly hard to scan in one pass.

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 takes on documenting return fields and does so thoroughly, plus tells the agent the next call. Enough to use it correctly, though a note on ordering or pagination is absent.

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, but the description adds meaning: `product` is confirmed to be the product slug / stable id, and `deliver_to_country` is tied to the 'lowest total' figure returned. Only `locale` is left unaddressed.

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 the resource precisely (variants of one product) and enumerates what each variant carries, so an agent knows exactly what comes back. It routes to get_product by id, distinguishing it from that sibling, though it never contrasts with search_products or product_rows.

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?

'Use it to switch from a card to the exact variant the buyer asked for, then get_product with that id' gives an explicit trigger and follow-up call. The edge case 'A product without siblings answers itself only' sets expectations, but no when-not-to-use condition is stated.

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