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

Annotations already indicate this is not read-only and not destructive, so basic mutation behavior is known. The description adds the constraint that it operates on an existing product, but provides no further detail on side effects, prerequisites beyond product existence, or error behavior. This is a minimal but not misleading disclosure.

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?

The description is a single, concise sentence that front-loads the action and resource, with no redundant words. It is efficiently written and easy to parse.

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?

Given the schema fully documents all parameters and an output schema exists, the description provides the essential purpose and target context. It is concise but sufficient for understanding the tool's role, though it does not elaborate on the product-variation hierarchy or any complex behaviors beyond the schema.

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% for all 9 parameters, so the schema already fully documents each parameter's meaning. The description itself adds no additional semantic information beyond the schema, matching the baseline for full coverage.

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?

The description uses a specific verb 'Add' and clearly identifies the resource ('a variation') and the target ('an existing product'), with examples (size, color). It distinguishes from sibling create_product by emphasizing 'existing product'.

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 implies when to use the tool (adding a variation to an existing product) but does not explicitly exclude alternatives or name them, such as create_product for new products. Guidance is clear in context but lacks explicit when-not-to-use or alternative references.

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