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

Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds the configuration prerequisite but says nothing about whether adding a duplicate product merges line items, how quantity behaves on repeat adds, or what errors result from missing option ids. With annotations doing the safety lift, this is adequate but thin.

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 sentences, no waste, with the action front-loaded and the prerequisite immediately after. Nothing could be cut without losing information.

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?

An output schema exists, so return values need not be explained. However, for a non-destructive mutation tool the description omits cart-state behavior (duplicate handling, line-item identity) that an agent would want before calling. It is minimally sufficient rather than complete.

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%, so all five parameters are already documented in the schema. The description adds only the provenance hint that option ids come from product_configure; it offers no extra detail on storeId, quantity, or notes semantics.

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 configured product to the cart"), which is enough to separate it from cart_remove_item, cart_update_item and cart_get. It does not explicitly contrast with the nearest sibling (cart_update_item), but the action is unambiguous.

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?

Gives an explicit prerequisite workflow: run product_configure first to obtain required variant option ids. That is real when-to-use guidance an agent would otherwise have to infer. It stops short of stating exclusions, e.g. when to use cart_update_item for an item already in the cart.

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