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

Annotations already declare readOnlyHint=false, idempotentHint=true, and destructiveHint=true, so the description is not obligated to restate safety. It still adds real value beyond them: 'Only the fields you pass change' documents partial-update semantics, and the write_products scope plus PUT endpoint disclose auth and transport. It does not explain why the operation is flagged destructive or what a successful response contains, keeping it below 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?

Four short sentences, each carrying distinct information (mutation type, mutable fields, partial-update rule, stock alternative, scope, endpoint). The 'WRITE' token is front-loaded so an agent sees the operation class immediately.

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?

Covers authorization, the partial-update contract, the sibling route for inventory, and the underlying endpoint — enough for an agent to call it correctly given annotations supply the safety profile and there is no output schema. It stops short of describing error conditions or whether unknown variant IDs fail loudly.

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 100%, so every parameter is already documented, including units ('store's primary currency') and bounds. The description's field list mirrors the schema rather than adding syntax, format, or edge-case guidance, so the baseline 3 applies.

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?

Opens with an explicit 'WRITE' marker and a specific verb+resource ('Change one variant's ...'), then enumerates exactly which fields are mutable. An agent can distinguish this from easystore_list_product_variants and easystore_adjust_inventory_level without opening a schema.

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?

States the exclusion explicitly ('To change stock use the inventory tools'), names the required scope ('Needs write_products'), and gives the endpoint. The alternative path for stock mutation is spelled out rather than left to inference.

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