Add a product to the cart

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

Annotations already declare this is a non-read-only, non-idempotent, non-destructive, open-world mutation, so the bar is lower. The description's one extra fact (no order is created) is a genuine boundary, but it omits whether repeated calls stack quantities, whether an existing line item is replaced, and whether login is required.

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?

Two short, front-loaded sentences with no filler, and the scoping caveat follows the action statement. It is efficient, though its brevity borders on under-specification for a mutation tool.

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?

For a simple two-parameter tool with reasonable annotation coverage and no output schema, the definition is close to sufficient. Missing quantity semantics and merge-on-duplicate behavior are the main gaps an agent would need to call it 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?

Schema coverage is only 50%: product_id is documented in the schema, while 'count' has only type/default/min/max constraints and no explanation of whether it sets or increments the line quantity. The description says nothing about either parameter and so fails to compensate for the coverage gap.

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?

States a specific verb and resource ('Add a product to the cart') that is immediately distinguishable from get_cart, remove_from_cart and clear_cart. It does not, however, differentiate itself from the very similar sibling add_recipe_to_cart, which a selecting agent would need.

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?

'Does not place an order' is a useful negative boundary that rules out treating this as checkout. But there is no positive guidance on when to prefer this over add_recipe_to_cart, nor any prerequisite such as needing a product_id from search_products or a completed login.

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