add

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

There are no annotations, so the description must fully disclose behavioral traits. It only states the action and input requirements, with no mention of side effects (e.g., whether existing cart items are updated or replaced), idempotency, authentication, or what the response contains. This is a significant gap for a mutating operation.

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 very short and front-loaded, with only two sentences and no filler. The fragment 'Need SKU and price_cents from search' is terse and actionable, though slightly informal. It earns a high conciseness score for its compactness, though it sacrifices completeness.

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 has no annotations, no output schema, and three parameters, the description is far too minimal. It doesn't explain what the function returns, how errors are handled, how 'qty' interacts with the cart, or any side effects. The mention of search is helpful, but overall the description is insufficient for an agent to confidently use the tool in all cases.

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?

With 0% schema description coverage, the description must compensate by explaining all parameters. It explicitly mentions SKU and price_cents (mapped to 'cents'), which adds meaning to those two properties. However, the optional 'qty' parameter is completely unexplained, leaving a gap for an important aspect of the operation.

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 function with a verb and resource: 'Add to cart.' It also mentions the prerequisite inputs (SKU and price_cents), which helps differentiate it from other cart-related tools like 'remove' or 'cart_diff'. However, it doesn't explicitly state what kind of item is added (e.g., product, offer), leaving some ambiguity.

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: after a search, since it says 'Need SKU and price_cents from search.' This gives a clear context. However, it does not provide explicit comparisons or exclusions relative to sibling tools like 'add_plan' or 'cart_diff', so the usage guidance is somewhat implicit rather than directive.

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