cart_add

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

The description adds detail beyond the `destructiveHint: true` annotation by explaining that `confirm=true` executes and verifies the addition, and returns an error if the item wasn't added. It does not mention other side effects (e.g., cart state changes), but the verification behavior is well described.

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 concise with a clear structure: main action, preview vs. execution, important parameter guidance, and error behavior. It is front-loaded and uses bullet points effectively without unnecessary text.

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 tool's simplicity, the presence of an output schema (context signal), and the sibling tools, the description covers all necessary aspects: the action, verification, parameter relationships, and error handling. It is complete for an agent to use correctly.

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?

Although the schema already covers all parameters (100% coverage), the description adds critical value by explaining the relationship between `product_id` (short ID) and `sku_id` (long ID) and how they come from search results. This goes beyond the schema's individual 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 the tool's action: 'Add an item to the shopping cart with verification.' It specifies the preview vs. execution behavior and distinguishes itself from siblings like `cart_add_many` and `cart_add_with_retry` by focusing on single-item addition with verification.

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 explains when to use `confirm` (preview vs. execution) and provides guidance on using both `product_id` and `sku_id` from search results. It does not explicitly state when to use alternatives like `cart_add_many`, but the context is clear enough for an agent to differentiate.

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