create_store_product_variant

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

Beyond annotations (readOnlyHint=false, destructiveHint=false), the description adds authentication via API key, max 10 concurrent requests, and respect for read-only and dry-run modes. This provides essential behavioral context for safe invocation.

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 well-structured with a clear opening, usage context, behavioral notes, and parameter docs. It is slightly verbose but front-loaded with the essential purpose, earning a high score for efficiency.

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?

The description covers purpose, usage context, authentication, concurrency, parameter details, and return value. With an output schema present, the description need not elaborate return fields. However, it leaves out error handling and idempotency details, which are acceptable given annotations.

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?

Despite 0% schema description coverage, the description includes a detailed parameter list explaining each argument, including additional_fields with examples of mergeable keys (url, sku, price, etc.). This significantly compensates for the schema's lack of descriptions.

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 clearly states 'Add a new variant to an existing product in a store' and elaborates that it represents a distinct SKU, size, or color. This distinguishes it from sibling tools like create_store_product or create_store_product_image.

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 provides context that many stores sync variants automatically via integrations, and this manual write suits custom or headless storefronts. It implies when to use this tool versus relying on integrations, though it does not explicitly list alternatives.

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