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

Annotations already cover read-only, idempotent and non-destructive behavior, and the description adds meaningful context beyond them: 'Members only' auth, the formula 'quant (-1 unlimited)', and the semantic weight of 'This is the truth the checkout consults'. It does not disclose any rate/limit or pagination behavior, so it falls short of a 5.

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?

One densely packed sentence that front-loads verb+resource, then the returned fields, then behavioral notes and a doc link. The long field enumeration is justified because there is no output schema, but the run-on construction is slightly harder to parse than a tighter phrasing would be.

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, no-output-schema read tool, the definition covers everything an agent needs: what it lists, the fields it returns, the shop-domain meaning, the membership requirement, and a docs link. Annotations carry the safety profile, so nothing material is missing.

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 both projectId and productIds are already documented, including the cross-reference to listRikmaProducts. The description only loosely reinforces this by scoping variants to 'products of one rikma' and naming productId among returned fields; it adds no syntax or constraint detail, so baseline 3 is appropriate.

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 (List) and resource (variant rows / product-variant / SKU) scoped to 'products of one rikma', and even enumerates the returned fields. This clearly distinguishes it from listRikmaProductsTool and listRikmaProductOptionsTool, which operate on products and options rather than SKU-level variants.

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?

Adds an auth prerequisite ('Members only') and implies the input by saying variants belong to products of one rikma, but never states when to prefer this over listRikmaProductsTool or getRikmaProductTool. Usage is inferable rather than explicit, which fits the 'implied usage' bar.

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