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

Annotations already mark the tool as destructive and not read-only. The description adds meaningful behavioral context: operations are applied in a strict order, quantity updates do not trigger re-quoting, additions are quoted, and the complete cart is returned. This goes beyond the annotations without contradicting them.

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 a single, compact sentence that front-loads the critical information: operation order, quoting behavior, and return value. Every part earns its place, and there is no redundant or vague wording.

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 multi-operation mutation tool with no output schema, the description provides the essential behavioral contract: what operations are applied, in what order, and what is returned. It could be slightly more explicit about destructive side effects, but the annotations and schema cover the remaining details.

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%, and the schema already provides detailed explanations for each parameter, including line IDs, quantities, and selection structures. The description contributes operation-level semantics but does not need to restate parameter details, so the baseline score of 3 is appropriate.

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 identifies the tool as a cart-modification operation, enumerates the three operation types (remove, update, add), specifies their execution order, and states the return value. This makes it easy to distinguish from sibling cart tools like create_cart, get_cart, and delete_cart.

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 establishes when this tool is appropriate: modifying an existing cart with removals, quantity changes, or additions. It also adds important usage caveats about quoting behavior (update without re-quoting, add with quoting). It does not explicitly name alternatives or exclusion cases, but the context and sibling list make the intended usage sufficiently clear.

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